Layered MAX phases (M: transition metal, A: III-A, IV-A group elements, X: C or N) are the parent materials of MXenes, which have recently received attention as a new atomic layer system and are known as industrial materials for applications owing to their excellent properties, which combine the characteristics of both metals and ceramics. Meanwhile, the bulk electronic structure of MAX phases has primarily been investigated using computational methods, primarily because well-characterized single crystals are few. This review presents anomalous electronic states such as Dirac points and line nodes, which have been observed in recent electronic structure studies pertaining to MAX phase single-crystals using angle-resolved photoemission spectroscopy. These states are expected to result in unique topological quantum transport in MAX phases.

The phase-field method is a continuum model used to calculate internal microstructure developments in various materials. Over the past four decades, it has become one of the primary approaches for analyzing microstructures in materials. During this time, both computational thermodynamics (e.g., the CALPHAD method) and material property calculations based on microstructure data have also advanced significantly. Together, these methods are evolving into a robust system that supports multiple aspects of material design. Additionally, data-driven engineering methods can be broadly viewed as a collection of tools for handling forward and inverse models in computational engineering. This tutorial review explores perspectives on the next generation of material design by integrating these approaches.

Nuclear medicine is a powerful clinical diagnostic tool for early cancer detection and characterization. In this review, we explore the potential of future nuclear medical imaging technology using MeV photons compared to advanced optical imaging technology employing eV photons. Specifically, we discuss three main topics within the framework of the MeV energy regime: (1) Multi-color and multi-wavelength imaging, (2) molecular interaction imaging with a quantum sensor, and (3) imaging enhancement utilizing quantum entanglement features.

A device that converts thermal energy into extractable forms, such as mechanical energy, is termed as a heat engine. The operating medium that powers the heat engine is usually a physical system that follows classical physics. In recent years, research on heat engines, whose operating media follow quantum physics, has been progressing from theoretical and experimental perspectives. In this study, we focus primarily on the theoretical aspects, particularly on how the performance of this type of quantum heat engine improves with an increase in the size of the operating medium. We discuss the research background, recent trends in this field, and our latest findings. The results presented here suggest a significant potential for enhancing heat engine performance by leveraging quantum mechanics as the operating principle.

Materials informatics has significantly advanced the prediction technology for new materials. However, not all predicted materials can be synthesized. We have been developing synthesis techniques to handle metastable states and achieve more new materials. This article presents the methods to change the chemical composition while preserving crystal structures by controlling the diffusion of specific constituent elements.

Time-domain reflectometry is an electrical measurement that utilizes the reflected waves of high-frequency electrical signals from portions where impedances are not matched in the high-frequency transmission paths. In the past, it has been used for large-scale measurements such as geological surveys. However, in recent years, technological advances have made it possible to perform small-scale measurements such as LSI quality diagnosis. We adopted this measurement to observe the carrier dynamics in electronic devices by measuring the transient impedance. This paper presents the results of a time-resolved analysis of organic thin-film transistors and organic solar cells.

As AI technology evolves and the demand for high-performance computing increases, high-capacity, low-power, and high-bandwidth memory is becoming more important. However, we are reaching the technical difficulty of achieving two-dimensional device scaling and computer architectures with off-chip memory. This article introduces a research progress on oxide-based 3D-integrated memory devices to break through this difficulty. In particular, the research on the memory devices using HfO₂-based ferroelectrics as memory element and oxide semiconductor as channel material is discussed.

The role of light is expanding beyond communication and measurement to include computing, as observed in the remarkable progress of artificial intelligence (AI) in the midst of the further digitization of society. This paper reviews the latest developments in photonic research aimed at enhancing reinforcement learning and decision-making tasks, both of which are fundamental functions of AI. We introduce methods for solving the multi-armed bandit problem using chaotic itinerancy of semiconductor laser dynamics and provide an overview of collective decision making that leverages quantum light interference.

Decommissioning preparations, including the research and development of solar cell-based radiation detection devices (SRDs) for reactor-internal radiation monitoring systems, are underway following the accident at the Fukushima Daiichi nuclear power plant. SRDs use the principle of electron–hole pairs generated by the incident radiation energy to output a current to an external circuit by the built-in potential. InGaP, CIGS, CdTe, and HOIP have been selected as candidates for radiation-tolerant solar cells for use in high radiation environments. This report presents the development of a radiation detection system using InGaP solar cells, a dynamic range estimation method using visible light, and work on neutron radiation detection.

High-temperature superconductor REBa₂Cu₃O_y (REBCO) microwave devices offer excellent performance. Microwave receive filters using REBCO film have excellent performance with low loss and sharp skirt characteristics and are already used in the receiving systems of mobile communication systems. However, practical applications of microwave devices using REBCO films are limited to receive filters. One reasons for the lack of progress is the low characteristics of the REBCO thin film. Recently, we reported that the characteristics of the REBCO thin film can be significantly improved via metal organic deposition using the trifluoroacetate (TFA-MOD) method and substrate annealing process. Herein, we introduce the TFA-MOD method and substrate annealing for the fabrication of REBCO thin films for high-frequency applications and demonstrate superconducting high-frequency devices based on these films.

Nanopore measurement is a method for the label-free detection and analysis of single biomolecules passing through nano-sized pores. Nanopores are broadly classified into protein and solid-state nanopores. Protein nanopore-based DNA sequencers have garnered significant attention as next-generation sequencers. Conversely, research advancements in solid-state nanopores, which entered the field more recently, have demonstrated significant progress in recent years. This review article outlines solid-state nanopore fabrication methods and introduces a novel photothermal-etching-assisted nanopore fabrication method.

Thermoelectric generators are solid-state devices capable of directly converting heat to electricity. The performance of these modules is limited by the tendency of the metal–semiconductor contacts at the hot-side to degrade due to chemical reactions and/or elemental diffusion. Transverse thermoelectric modules can be employed to address these issues because the temperature gradient and electricity are orthogonal to one another. Consequently, the exposure of metal–semiconductor contacts to high-temperature environments can be avoided, thereby improving the long-term thermal stability of the device. One approach to designing transverse thermoelectric devices is to use materials having goniopolarity, which simultaneously exhibit p- and n-type conduction along different crystallographic directions. Here, we report the goniopolarity of Mg₃Sb₂ and Mg₃Bi₂ due to their band anisotropy.

The dielectric ceramics used in multilayer ceramic capacitors (MLCCs) require not only a high dielectric permittivity but also a high dielectric breakdown strength, which is achieved by precisely controlling the microstructure. The hydrothermal method, which is one of the liquid-phase synthesis methods, is effective at synthesizing well-dispersed dielectric particles with a small particle size, which can be sintered to obtain dense and fine-grained dielectric ceramics. This paper presents our recent attempts to develop new dielectric ceramics using the hydrothermal method, focusing on bismuth potassium titanate-based materials.

Liposomes are lipid vesicles with a cell-like bilayer membrane structure that are used to construct artificial cell models. To ensure the reproducibility of experiments and enable quantitative analysis, a method for producing liposomes with uniform size and high encapsulation efficiency is required. Recently, we developed a system for generating monodisperse liposomes using a microfluidic device. This system can produce monodisperse liposomes with diameters ranging from 25 to 45 µm, achieving a yield of approximately 100%. To apply this system to the construction of artificial cells, we present the results of encapsulating an in vitro transcription/translation system in liposomes to investigate the conditions under which protein synthesis occurs.