2025 ASUNARO Grant awarded to four researchers

Our current universe is made of matter. While this might seem obvious, when the universe was born, antimatter, which has opposite properties to matter, was created in equal amounts together with matter. Since matter and antimatter annihilate each other when they collide, nothing should have remained. However, for some unknown reason, matter had a tiny surplus over antimatter (just one part in a billion), which led to our current matter-dominated universe. It remains one of the greatest unsolved puzzles in modern physics.
One of the necessary conditions for creating a matter-dominated universe (known as Sakharov’s three conditions) is the existence of processes that don’t conserve baryon number. Neutron-antineutron oscillation is predicted to be one such process. We plan a future experiment at a research reactor, in which we will trap ultracold neutrons in a storage bottle to search for neutron-antineutron oscillations. However, we don’t fully understand what happens when antineutrons hit a bottle wall.
This research aims to study low-energy antineutron production at CERN’s Antiproton Decelerator (AD) facility, to conduct scattering experiments between low-energy antineutrons and atomic nuclei.

By harnessing the unique enzymatic reactions acquired through evolution, it may be possible to perform chemical transformations under mild conditions that are difficult to achieve using conventional chemical synthesis. One such example is the synthesis of polycyclopropanated chains, which are expected to serve as high-energy-density fuel molecules. While microorganisms can produce these structures efficiently using enzymatic reactions, the underlying mechanism remains poorly understood. This biosynthetic process involves three enzymes—Jaw4, Jaw5, Jaw6. Among them, Jaw5 belongs to the radical SAM enzyme superfamily and is particularly difficult to study due to its instability in air. We have established a method for analyzing enzyme reactions in an inert gas environment, which is expected to be suitable for the study of Jaw5. In this study, we aim to characterize the catalytic activities of Jaw4, Jaw5, and Jaw6 in vitro and to uncover the novel chemistry that enables the synthesis of polycyclopropanated chains under aqueous, ambient temperature and pressure conditions.

Cells convert chemical energy into mechanical work to remodel their cytoskeletons, allowing for deformation and locomotion. Inspired by this, autonomous motion of oil droplets on water surfaces has emerged as a simple yet insightful model for studying non-equilibrium systems with cell-like dynamics.
In this study, we focus on the non-linear oscillatory behavior of oil droplets driven by interfacial tension gradients in the presence of surfactants. A theoretical model is proposed to describe the oscillation mechanism, and experimental validation is performed. By varying the structure and properties of surfactants, as well as introducing chemical reactions in the oil phase, we aim to control the motion characteristics of the droplets. This system offers a minimal model for environmentally responsive behaviors akin to contraction and migration observed in living cells.

Electrolytic reactions are known to be environmentally friendly chemical processes, with applications across energy, automotive, and electronic industries. Electrolytes play crucial roles in the electrochemical reactions. Supercritical carbon dioxide (scCO₂)-H₂O co-solvent electrolytes composed of scCO₂, water, and surfactants, are unique electrolytes due to their dual characteristics. They form kinetically stable emulsions under mechanical stirring, while the phase separation between scCO₂ and H₂O occurs thermodynamically under static conditions.
The objective of this study is to clarify the effects of their dual characteristics on the electron transfer processes between the substrate and the electrode. To this end, the deposition behavior of electrodeposited metal films and electrodeposited conducting polymer films prepared with the scCO₂-H₂O co-solvent electrolytes is evaluated. This fundamental knowledge about the scCO₂-H₂O co-solvent electrolytes will contribute to the establishment of the platform for various functional material fabrications.