다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

We introduce the 2D counterpart of layered black phosphorus, which we call phosphorene, as an unexplored p-type semiconducting material. Same as graphene and MoS2, single-layer phosphorene is flexible and can be mechanically exfoliated. We find phosphorene to be stable and, unlike graphene, to have an inherent, direct, and appreciable band gap. Our ab initio calculations indicate that the band gap is direct, depends on the number of layers and the in-layer strain, and is significantly larger than the bulk value of 0.31–0.36 eV. The observed photoluminescence peak of single-layer phosphorene in the visible optical range confirms that the band gap is larger than that of the bulk system. Our transport studies indicate a hole mobility that reflects the structural anisotropy of phosphorene and complements n-type MoS2. At room temperature, our few-layer phosphorene field-effect transistors with 1.0 μm channel length display a high on-current of 194 mA/mm, a high hole field-effect mobility of 286 cm2/V·s, and an...

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Phosphorene: An Unexplored 2D Semiconductor with a High Hole Mobility

There is still an ongoing effort to search for sustainable, clean and highly efficient energy generation to satisfy the energy needs of modern society. Among various advanced technologies, electrocatalysis for the oxygen evolution reaction (OER) plays a key role and numerous new electrocatalysts have been developed to improve the efficiency of gas evolution. Along the way, enormous effort has been devoted to finding high-performance electrocatalysts, which has also stimulated the invention of new techniques to investigate the properties of materials or the fundamental mechanism of the OER. This accumulated knowledge not only establishes the foundation of the mechanism of the OER, but also points out the important criteria for a good electrocatalyst based on a variety of studies. Even though it may be difficult to include all cases, the aim of this review is to inspect the current progress and offer a comprehensive insight toward the OER. This review begins with examining the theoretical principles of electrode kinetics and some measurement criteria for achieving a fair evaluation among the catalysts. The second part of this review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting. Attention of this review is also paid to in situ approaches to electrocatalytic behavior during OER, and this information is crucial and can provide efficient strategies to design perfect electrocatalysts for OER. Finally, the OER mechanism from the perspective of both recent experimental and theoretical investigations is discussed, as well as probable strategies for improving OER performance with regards to future developments.

Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives

Preceding the current interest in layered materials for electronic applications, research in the 1960's found that black phosphorus combines high carrier mobility with a fundamental band gap. We introduce its counterpart, dubbed few-layer phosphorene, as a new 2D p-type material. Same as graphene and MoS2, phosphorene is flexible and can be mechanically exfoliated. We find phosphorene to be stable and, unlike graphene, to have an inherent, direct and appreciable band-gap that depends on the number of layers. Our transport studies indicate a carrier mobility that reflects its structural anisotropy and is superior to MoS2. At room temperature, our phosphorene field-effect transistors with 1.0 um channel length display a high on-current of 194 mA/mm, a high hole field-effect mobility of 286 cm2/Vs, and an on/off ratio up to 1E4. We demonstrate the possibility of phosphorene integration by constructing the first 2D CMOS inverter of phosphorene PMOS and MoS2 NMOS transistors.

Phosphorene: A New 2D Material with High Carrier Mobility

Magnetism and ferroelectricity are essential to many forms of current technology, and the quest for multiferroic materials, where these two phenomena are intimately coupled, is of great technological and fundamental importance. Ferroelectricity and magnetism tend to be mutually exclusive and interact weakly with each other when they coexist. The exciting new development is the discovery that even a weak magnetoelectric interaction can lead to spectacular cross-coupling effects when it induces electric polarization in a magnetically ordered state. Such magnetic ferroelectricity, showing an unprecedented sensitivity to ap plied magnetic fields, occurs in 'frustrated magnets' with competing interactions between spins and complex magnetic orders. We summarize key experimental findings and the current theoretical understanding of these phenomena, which have great potential for tuneable multifunctional devices.

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Multiferroics: a magnetic twist for ferroelectricity

Chiral Soliton Lattice in Chiral Magnetic Crystal CrNb3S6

The mechanical properties of metallic materials can be controlled by both alloy design and the construction of an appropriate structure. Porous materials are a promising candidate for bone-related devices because they have a low Young’s modulus and allow bone ingrowth. Recently, great advancements have been made in additive manufacturing technology, also known as three-dimensional printing. This technology enables the arbitrary and independent control of the Young’s modulus, strength of the material, the shape and volume fraction of the pores. Porous titanium samples composed of rhombicuboctahedron-derived units with sub-millimetre dimensions were fabricated by laser additive manufacturing, and the dependence of their mechanical properties on the structural parameters was investigated. Porous Ti samples with five different sets of dimensions were accurately fabricated as designed. The solid Ti parts of the samples were confirmed to contain no remarkable solidification voids by Archimedes’ principle. The porosity can be easily controlled in the present structural design; the measured and designed porosities showed a good linear relationship, although the measured porosity was slightly larger than the designed porosity. The gradient of stress-strain curve in elastic region can be also arbitrarily controlled in porous Ti samples with the present structure; it increased as the minimum cross-sectional area ratio in the plane perpendicular to the loading axis increased. This means that Young’s modulus can be arbitrarily controlled by the present structural control. However, it should be noted that the local mechanical properties such as Young’s modulus of the fabricated samples are not uniform in the overall structures; to improve this, the effect of the structure on the retention and flow of heat must be considered. [doi:10.2320/matertrans.ME201916]

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Mechanical Properties of Additively Manufactured Porous Titanium with Sub-Millimetre Structural Units

A mixed-oxide system (1 − x)Pb(Zn1/3Nb2/3)O3–xPbTiO3, which has a simple perovskite structure, has been reported to exhibit remarkable piezoelectric responses for 0 < x ≤ 0.08. To understand the fe...

Features of Ferroelectric States in the Simple-Perovskite Mixed-Oxide System (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 with Lower Ti Contents

Observation of magnetic domains is important in understanding the magnetic properties of magnetic materials and devices. In this paper, we report that the magnetic domains of M-type hexaferrites with uniaxial anisotropy can be visualized via small-angle electron diffraction and Foucault imaging. The position of the diffraction spots has the same period as that of magnetic domains in a Sc-substituted hexaferrite (BaFe12-x-? Sc x Mg ? O19). Conversely, the spots were observed four times longer than the period of magnetic domains in hexaferrite without substitution (BaFe12O19), demonstrating the long-range order of the Bloch walls. When the specimen was tilted, the magnetic deflection effect, as well as the periodic spots of magnetic domains, occurred. Thus, we were able to visualize the magnetic domains with different magnetization directions and domain orientations by selecting deflection spots. The results indicate that the technique utilized in this study is useful in observing the magnetic materials with uniaxial anisotropy.

https://robots.iopscience.iop.org/article/10.7567/1347-4065/ab13dc/pdf

Observation of magnetic domains in uniaxial magnets via small-angle electron diffraction and Foucault imaging

We report a polar ordering of electrons in RFe 2 O 4 , which consistently explains the ferroelectric property of this material. Pyroelectric current measurement, low frequency AC dielectric constants, resonant X-ray scattering diffraction experiment and the consideration for the charge frustration, consistently lead the presence of ferroelectricity originated from the ordering of Fe 3+ and Fe 2+ . The ferroelectric material originated from the polar electron distribution and free from the ionic displacement may potentially have great possibilities in future applications and fundamental researches.

Shigeo Mori

Papers

Chiral Soliton Lattice in Chiral Magnetic Crystal CrNb3S6

Mechanical Properties of Additively Manufactured Porous Titanium with Sub-Millimetre Structural Units

Features of Ferroelectric States in the Simple-Perovskite Mixed-Oxide System (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 with Lower Ti Contents

Observation of magnetic domains in uniaxial magnets via small-angle electron diffraction and Foucault imaging

Ferroelectricity from Valence Ordering in RFe2O4