Kyushu University · Materials Science
Professor Koichiro Kato's research lab specializes in computational quantum chemistry and materials science, focusing on first-principles electronic structure calculations using advanced methods such as the fragment molecular orbital (FMO) approach. The lab investigates molecular interactions, electronic properties, and reactivity in complex systems ranging from biomolecules and drug targets to carbon nanotubes and polymer surfaces. Key research directions include accurate prediction of atomic partial charges for drug design, understanding electronic polarization in biomolecules, and analyzing molecular interactions in viral proteins and functional materials. The lab combines high-accuracy quantum mechanical simulations with machine learning to enable efficient and precise modeling of large and complex systems.
Figures are computed from collected data and may differ slightly.
Here, we have constructed neural network-based models that predict atomic partial charges with high accuracy at low computational cost. The models were trained using high-quality data acquired from quantum mechanics calculations using the fragment molecular orbital method. We have succeeded in obtaining highly accurate atomic partial charges for three representative molecular systems of proteins, including one large biomolecule (approx. 2000 atoms). The novelty of our approach is the ability to
The expressions of cytokeratin 8 and 18 (CK8 and CK18) in the normal canine skin (2 cases) and cutaneous adnexal tumors (127 cases) were investigated immunohistochemically. In the normal skin, co-expression of CK8/18 was found in the glandular epithelium of apocrine sweat glands, and single CK8-immunoreactivity was detected occasionally in the external root sheath at the isthmus and suprabulbar regions of the hair follicles. Neoplastic glandular epithelial cells in all apocrine gland tumors (21/
SARS-CoV-2 is the causative agent of coronavirus (known as COVID-19), the virus causing the current pandemic. There are ongoing research studies to develop effective therapeutics and vaccines against COVID-19 using various methods and many results have been published. The structure-based drug design of SARS-CoV-2-related proteins is promising, however, reliable information regarding the structural and intra- and intermolecular interactions is required. We have conducted studies based on the frag
We perform a systematic first-principles study of energetics and electronic properties of chiral carbon nanotubes (CNTs) in the density-functional theory. It is found that chiral CNTs possess slightly twisted ground-state geometries. Moderate-diameter CNTs show twisting-dependent electronic properties well classified by their chiral indices, while the electronic structures of small-diameter CNTs possess sizable but individually different twisting dependences, leading to metal-semiconductor trans
Abstract 2,4‐Dinitrophenylhydrazones formed by the reaction of 2,4‐dinitrophenylhydrazine with carbonyl groups were formed in polyethylene film oxidized with chromic acid mixture. The changes in amount of the hydrazones formed in the films were inferred by comparing the absorptions in the ultraviolet spectra and compared with changes in wettability with water of the films. In the early stage of treatment with chromic acid mixture, the hydrazone amount increased and the contact angle of water dec
Abstract The hydrazones of the acetophenone‐type 2,4‐dinitrophenyihydrazone, formed by the reaction between 2,4‐dinitrophenylhydrazine and carbonyl groups, was formed on the surface zone of irradiated polystyrene film. The changes in the amount of hydrazones formed on the films were inferred by comparing the absorptions in the ultraviolet and infrared spectra. The amounts of hydrazones formed increased with increase in irradiation time within about 3 hr and approached an asymptote with increase
Anion exchange membranes (AEMs) are core components in fuel cells and water electrolyzers, which are crucial to realize a sustainable hydrogen society. The low anion conductivity and durability of AEMs have hindered the commercialization of AEM-based devices, and research and development (R&D) to improve AEM materials is often resource-intensive. Although machine learning (ML) is commonly used in many fields to accelerate R&D while reducing resource consumption, it is rarely used in the AEM fiel
Abstract Calcite is a biomineral extensively studied as a typical example to elucidate the mechanism of biomineralization. It is known that the surface of calcite adsorbs Asp-rich peptides to initialize the biomineralization. However, understanding of the microscopic mechanism of the adsorption is still insufficient. We hence analyzed interaction energies based on the quantum mechanical calculation between calcite and Asp-rich peptides by using the fragment molecular orbital method. We quantitat
2,4-Dinitrophenylhydrazine was reacted on polyethylene films irradiated in air with ultraviolet light. The changes in amount of carbonyl groups and 2,4-dinitrophenyl-hydrazones formed in the films were inferred by comparing their absorptions in the infrared and ultraviolet spectra, respectively. The amount of hydrazones formed increased with increase in the reaction time, and rates of the increase gradually decreased with increase in the reaction time. A comparison of the change in amount of hyd
High-density polyethylene films were treated with chromic acid mixture at 70°C. The treated films were then reacted with 2,4-Dinitrophenylhydrazine. The changes in the amounts of carbonyl groups and 2,4-dinitrophenylhydrazones formed in the films were estimated by comparing their absorptions in the infrared and ultraviolet spectra, respectively. Scanning electron micrographs of the treated film surfaces were taken. Oxidation of the film surface zone, etching of the film surface zone, and oxidati
Abstract Polyethylene films were irradiated in air by ultraviolet light. 2,4‐Dinitrophenylhydrazine was reacted on the irradiated films. The changes in amounts of carbonyl groups and 2,4‐dinitrophenynlhydrazones formed in the films were inferred by comparing their absorptions in the infrared and ultraviolet spectra, respectively. It seems that the contents of carbonyl groups formed in the amorphous regions in the high‐density polyethylene films by the irradiation were larger than the contents of
Abstract We present the first-ever application of a statistical data analysis technique based on a persistent homology method combined with molecular dynamics simulations to determine the microscopic structure of water on graphene. This work assessed the rapid transition in the water structure on going from surface water to free water with increasing distance from the graphene surface, which is one of the most fundamental issues to be resolved in the field of water research. The crossover distan
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