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We have developed a simple and straightforward way to realize controlled postdoping toward 2D transition metal dichalcogenides (TMDs). The key idea is to use low-kinetic-energy dopant beams and a high-flux chalcogen beam simultaneously, leading to substitutional doping with controlled dopant densities. Atomic-resolution transmission electron microscopy has revealed that dopant atoms injected toward TMDs are incorporated substitutionally into the hexagonal framework of TMDs. The electronic properties of doped TMDs (Nb-doped WSe2) have shown drastic change and p-type action with more than 2 orders of magnitude increase in current. Position-selective doping has also been demonstrated by the postdoping toward TMDs with a patterned mask on the surface. The postdoping method developed in this work can be a versatile tool for 2D-based next-generation electronics in the future.

In condensed matter, phase separation is strongly related to ferroelasticity, ferroelectricity, ferromagnetism, electron correlation, and crystallography. These ferroics are important for nano-electronic devices such as non-volatile memory. However, the quantitative information regarding the lattice (atomic) structure at the border of phase separation is unclear in many cases. Thus, to design electronic devices on the molecular level, a quantitative relationship must be established between the lattice and the electrons. Herein, we elucidated a PdII–PdIV/PdIII–PdIII phase transition and phase separation mechanism for [Pd(cptn)2Br]Br2 (cptn = 1R,2R-diaminocyclopentane), propagated through a hydrogen-bonding network. Although the Pd···Pd distance was used to determine the electronic state, the differences in the Pd···Pd distance and the optical gap between Mott–Hubbard (MH) and charge-density-wave (CDW) states were only 0.012 Å and 0.17 eV, respectively. The N–H···Br···H–N hydrogen-bonding network functioned as a jack, adjusting the structural difference dynamically, and allowing visible ferroelastic phase transition/separation in a fluctuating N2 gas flow. In addition, the effect of the phase separation on the spin susceptibility and electrical conductivity were clarified to represent the quasi-epitaxial crystals among CDW–MH states. These results indicate that the phase transitions and separations could be controlled via modifications at the atomic and molecular levels, such as the addition of hydrogen bonding.

Monascus pigment is derived from red-mold rice fermented by monascus purpureus and utilized as a natural coloring agent and natural food additive in East Asia. Monascus pigment works as a radical scavenger. Some antioxidant combine cancer chemo-therapy to protect normal tissue because chemotherapy induce side effect for normal tissue. This combination therapy can attenuate the cytotoxicity of anti-cancer drugs by antioxidants effects. However, the effect of this combination therapy for cancer cells dose not investigate enough. In this study, we investigated the combination effect of anti-oxidants and anti-cancer drugs. We selected an anti-oxidant as monascus pigment and following four anti-cancer drugs: doxorubicin, tamoxifen, paclitaxicel, and cyclophosphamide. Combination treatment with monascus pigment and cyclophosphamide enhanced the cytotoxicity of cyclophosphamide. Moreover, this combination treatment accelerated apoptosis. The spot on TLC assay board of the monascus pigment and cyclophosphamide mixture is different from the spot of monascus pigment alone and cyclophosphamide alone. The interaction between monascus pigment and cyclo-phosphamide can produce some cytotoxicity compounds or accelerate intracellular cyclophosphamide accumulation. Hence, we concluded that the interaction of both cyclophosphamide and monascus pigment involved enhancement of cyclophosphamide cytotoxicity.

Studying the microscopic behavior of free carriers in materials at an ultrashort time scale is critical to developing semiconductor, optoelectronic, and other technologies satisfying the ever-incre...

We have combined atomic force microscopy with other techniques to reveal the mechanism of the actin filament and stress fibers formation processes that underlies the cell death process due to photodynamic therapy.

With the progress of infrared high-intensity pulse technology, the ultrafast control of electronic states has been attracting considerable attention. Most elementary excitations of solids have resonance energy in the mid-infrared (MIR) frequency domain. Therefore, to understand these dynamics in detail and open up new possibilities, new technological innovations are desired. In this study, we have developed a system that combines 8 fs near-infrared pulsed light with carrier envelope phase-controllable subcycle MIR and THz pulsed lights. This technology has produced a new method that enables the analysis of phase-sensitive phenomena in the near-infrared to far-infrared region.

Purpose Macrophages contribute to the progression of vascular inflammation, making them useful targets for imaging and treatment of vascular diseases. Gold nanoparticles (GNPs) are useful as computed tomography (CT) contrast agents and light absorbers in photothermal therapy. In this study, we aimed to assess the viability of macrophages incubated with GNPs after near-infrared (NIR) laser light exposure and to evaluate the utility of intravenously injected GNPs for in vivo imaging of vascular inflammation in mice using micro-CT. Procedures Mouse macrophage cells (RAW 264.7) were incubated with GNPs and assessed for GNP cellular uptake and cell viability before and after exposure to NIR laser light. For in vivo imaging, macrophage-rich atherosclerotic lesions were induced by carotid ligation in hyperlipidemic and diabetic FVB mice (n = 9). Abdominal aortic aneurysms (AAAs) were created by angiotensin II infusion in ApoE-deficient mice (n = 9). These mice were scanned with a micro-CT imaging system before and after the intravenous injection of GNPs. Results The CT attenuation values of macrophages incubated with GNPs were significantly higher than those of cells incubated without GNPs (p In vivo CT images showed higher CT attenuation values in diseased carotid arteries than in non-diseased contralateral arteries, although the difference was not statistically significant. The CT attenuation values of the perivascular area in AAAs of mice injected with GNPs were significantly higher than those of mice without injection (p = 0.0001). Conclusions Macrophages with GNPs had reduced viability upon NIR laser exposure. GNPs intravenously injected into mice accumulated in sites of vascular inflammation, allowing detection of carotid atherosclerosis and AAAs in CT imaging. Thus, GNPs have potential as multifunctional biologically compatible particles for the detection and therapy of vascular inflammation.

With the discovery of graphene, the excellent characteristics of graphite (multilayer graphene), such as high thermal and electric conductivities, heat resistance, and chemical stability, have also...

The in-plane connection and layer-by-layer stacking of atomically thin layered materials are expected to allow the fabrication of two-dimensional (2D) heterostructures with exotic physical properties and future engineering applications. However, it is currently necessary to develop a continuous growth process that allows the assembly of a wide variety of atomic layers without interface degradation, contamination, and/or alloying. Herein, we report the continuous heteroepitaxial growth of 2D multiheterostructures and nanoribbons based on layered transition metal dichalcogenide (TMDC) monolayers, employing metal organic liquid precursors with high supply controllability. This versatile process can avoid air exposure during growth process and enables the formation of in-plane heterostructures with ultraclean atomically sharp and zigzag-edge straight junctions without defects or alloy formation around the interface. For the samples grown directly on graphite, we have investigated the local electronic density of states of atomically sharp heterointerface by scanning tunneling microscopy and spectroscopy, together with first-principles calculations. These results demonstrate an approach to realizing diverse nanostructures such as atomic layer-based quantum wires and superlattices and suggest advanced applications in the fields of electronics and optoelectronics.

The recent development of optical technology has enabled the practical use of a carrier-envelope phase-controlled monocycle electric field in the terahertz (THz) regime. By combining this technique...

In current materials science and technologies, surface effects on carrier and spin dynamics in functional materials and devices are of great importance. In this paper, we present the surface-sensitive probing of electron spin dynamics, performed by optical-pump-probe scanning tunneling microscopy (OPP-STM). Time-resolved spin lifetime information on a manganese (Mn)-deposited GaAs(110) surface was successfully obtained for the first time. With increasing Mn density via in situ evaporation, a nonlinear change in the spin lifetime in the picosecond range was clearly observed, while directly confirming the Mn density by STM. In comparison with the results obtained by the conventional OPP method, we have also demonstrated that the observed nonlinear spin lifetime behavior was surface-mediated, which can be characterized using only the surface-sensitive OPP-STM technique.

A scanning probe microscope coupled with either femtosecond laser pulses or terahertz pulses holds great promise not only for observing ultrafast phenomena but also for fabricating desirable structures at the nanoscale. In this study, we demonstrate that a few-nanometer-scale phase change can be non-thermally stored on the Ge2Sb2Te5 surface by a laser-driven scanning tunneling microscope (STM). An atomically flat Ge2Sb2Te5 surface was irradiated with the optical near-field generated by introducing femtosecond laser pulses to the STM tip-sample junction. The STM topographic images showed that few-nanometer-scale mounds appeared after irradiation. In addition, tunneling conductance spectra showed that the bandgap increased by 0.2 eV in the area of 5 × 5 nm2. These indicate that the nanoscale crystal-to-amorphous phase change was induced by the STM-tip-induced near field. Our approach presented here offers an unprecedented increase in the recording density of optical storage devices and is, therefore, expected to facilitate the development of next-generation information technology.

Introduction: Inflammation contributes to progression of both atherosclerosis and abdominal aortic aneurysms (AAA). Gold nanoparticles (GNPs) have imaging and therapeutic properties, as they can ablate cells through optical excitation. We have shown that GNPs are taken up by vascular macrophages and can be used to detect murine carotid atherosclerosis and AAA with computed tomography (CT). In this study, we evaluated GNPs for optical ablation of macrophages in vitro and ex vivo. Methods: Mouse macrophage cells were incubated with or without 100 or 200 μg/ml of GNPs (15 nm) for 24 hours. Ten million cells with or without GNPs were exposed to near-infrared (NIR) laser light (830 nm, pulse width 200 femtosecond) for 10-20 minutes at 400-437 mW. After optical excitation, cells were incubated for 24 hours, and the viability was measured by MTT assay. Male apoE-deficient mice were subject to continuous angiotensin II infusion via subcutaneously implanted osmotic mini-pumps (N=4). After 2 weeks, mice were injected with GNPs (10 mg/mouse) via tail vein. At 48 hours post-injection, aortas were excised. Excised aortas were scanned with micro-CT imaging system and exposed to the laser for 20 minutes at 364 mW. After optical ablation, the sections of aortas were stained with anti-caspase-3 antibody. Results: With the higher dose of GNPs (200 μg/ml), cell viability was significantly reduced by in vitro optical excitation for 10 minutes (Figure 1, left; p Conclusion: Optical excitation of GNPs causes macrophage ablation and has potential for targeted nanotherapy of vascular inflammation.

Based on the data in the Japanese Science and Technology Indicators 2017 by the Ministry of Education, Culture, Sports, Science and Technology, the situation in which we are located and future possibilities are discussed.

We have developed a multiplex coherent anti-Stokes Raman scattering microscope effective for low-wavenumber measurement by combining a high-repetition supercontinuum light source of 1064 nm and a near-infrared high-sensitivity InGaAs diode array. This system could observe the low-wavenumber region down to 55 cm−1 with high sensitivity. In addition, using spectrum shaping and spectrum modulation techniques, we simultaneously realized a wide bandwidth (−1), high wavenumber resolution (9 cm−1), high efficiency, and increasing signal-to-noise ratio by reducing the effect of the background shape in the low-wavenumber region. Spatial variation of a sulfur crystal phase transition with metastable states was visualized.

Dabigatran is a novel oral anticoagulant that directly inhibits free and fibrin-bound thrombins and exerts rapid and predictable anticoagulant effects. While the use of this reagent has been associated with an increased risk of gastrointestinal bleeding, the reason why dabigatran use increases gastrointestinal bleeding risk remains unknown. We investigated the cytotoxicity of dabigatran etexilate and tartaric acid, the two primary components of dabigatran. The cytotoxicity of dabigatran etexilate and tartaric acid was measured in a cell viability assay. Intracellular mitochondrial reactive oxygen species (mitROS) production and lipid peroxidation were measured using fluorescence dyes. Cell membrane viscosity was measured using atomic force microscopy. The potential of ascorbic acid as an inhibitor of dabigatran cytotoxicity was also evaluated. The cytotoxicity of dabigatran etexilate was higher than that of tartaric acid. Dabigatran etexilate induced mitROS production and lipid peroxidation and altered the cell membrane viscosity. Ascorbic acid inhibited the cytotoxicity and mitROS production induced by dabigatran etexilate. Therefore, we attributed the cytotoxicity of dabigatran to dabigatran etexilate, and proposed that the cytotoxic effects of dabigatran etexilate are mediated via mitROS production. Additionally, we demonstrated that dabigatran cytotoxicity can be prevented via antioxidant treatment.

Modulation of the local density of states of single-wall carbon nanotubes (SWCNTs) is induced by the encapsulation of europium nanowires (EuNWs). The observation of these modulated density of states using scanning tunneling microscopy/spectroscopy combined with density functional theory calculations is reported. The electronic modulation of SWCNTs by encapsulation of EuNWs is revealed as a Fermi level shift, band gap reduction, and the emergence of localized states in the gap. The present results show that the electronic interaction between EuNWs and SWCNTs is much stronger than that previously reported for nanomaterials encapsulated in SWCNTs.

Carrier-envelope-phase-controlled single-cycle terahertz pulses can induce coherent electron tunnelling either from a Pt/Ir nanotip to a graphite sample or vice versa. The pulses enable ultrafast nonlinear manipulation of electrons at the atomic scale. The ultrafast coherent manipulation of electrons using waveform-controlled laser pulses1,2,3,4,5,6,7,8,9 is a key issue in the development of modern electronics10,11. Developing such an approach for a tunnel junction will provide a new platform for governing ultrafast currents on an even smaller scale, which will be indispensable for the advancement of next-generation quantum nanocircuits12,13,14,15 and plasmonic devices16,17,18. Here, we demonstrate that carrier-envelope-phase-controlled single-cycle terahertz electric fields can coherently drive electron tunnelling either from a nanotip to a sample or vice versa. Spatially confined electric fields of more than 10 V nm–1 strongly modulate the potential barrier at a nanogap in a scanning tunnelling microscope (STM) on the subpicosecond timescale and can steer a large number of electrons in an extremely nonlinear regime, which is not possible using a conventional STM. Our results are expected to pave the way for the future development of nanoscale science and technologies.

We report on pump-probe based helicity dependent time-resolved Kerr measurements under infrared excitation of chalcogenide superlattices, consisting of alternately stacked GeTe and Sb

We have investigated atomic and electronic structure of grain boundaries in monolayer MoS2, where relative angles between two different grains are 0 and 60 degree. The grain boundaries with specific relative angle have been formed with chemical vapor deposition (CVD) growth on graphite and hexagonal boron nitride flakes; van der Waals interlayer interaction between MoS2 and the flakes restricts the relative angle between two different grains of MoS2. Through scanning tunneling microscopy (STM) and spectroscopy measurements, we have found that the perfectly stitched structure between two different grains of MoS2 was realized in the case of the 0 degree grain boundary. We also found that even with the perfectly stitched structure, valence band maximum (VBM) and conduction band minimum (CBM) shows significant blue shift, which probably arise from lattice strain at the boundary.

Understanding of the dynamics of the bonding states of molecules with electrodes while the molecular conformation is changed is particularly important for elucidating the details of electrochemical devices as well as molecular devices in which the reaction dynamics of the electrodes and molecules plays an important role, such as in fuel cells, catalysis and bioelectrochemical devices. However, it has been difficult to make measurements when the distance between counter electrodes is short, namely, the molecule is raised from a lying form, almost parallel and close to the electrodes, toward a standing form and vice versa. We previously have developed a method called the three-dimensional (3D) dynamic probe method, which enables conductance measurement while the conformation of a single-molecule junction is precisely controlled by scanning tunneling microscopy (STM) techniques. Here, by combining this method with density functional theory (DFT) calculations, it has become possible to simultaneously consider the effects of the dynamics of molecular structures and the bonding states at the electrodes on the local transmission pathways, local-bond contributions to conductance. Here, by performing an analysis on 1,4-benzenediamine (BDA) and 1,4-benzenedithiol (BDT) single molecule junctions, we have observed, for the first time, the effect of a change in the molecular conformations and bonding states on the local transmission pathways for a short Au electrode distance condition.

Here, we report on our recent progresses of metal-organic chemical vapor deposition (CVD) growth of two-dimensional heterostructures based on transition metal dichalcogenide (TMDC) atomic layers. Controlling the precursor supply enables the formation of TMDC-based in-plane heterostructures with atomically straight junctions without defects or alloy formation around the interface. The present findings pave way for the simple and rapid synthesis of large scale, high quality TMDC-based heterostructures, quantum wires, and surperlattices.