In the repulsive desorption of hyperthermal products, rotation and translation are simultaneously excited by a common repulsion, resulting in mode coupling (MC). This review highlights the MC in repulsive desorption since it plays a key role in both the energy partitioning (EP) of the products to each mode and the structural sensitivity of desorption dynamics. It has long been overlooked due to non-angle-resolved (AR) energy analysis that ignores the desorption-angle dependence of the rotational and translational energies. The non-AR flux or energy analysis has prevented the desorption dynamics from being structure-sensitive since the structural information of desorption sites (symmetry, slope, and transition state orientation) can be extracted from the anisotropy of the product flux and energy distributions. Typical examples of the EP due to MC between translation and rotation include the combinative D₂ desorption on Cu(111), and the N₂ desorption from the decomposition of adsorbed N₂O on Pd(110)(1×1). For the former, the released energy is largely conserved in desorbed D₂ and the anti-correlation between the rotational and translational energies is clear. For the latter, the anti-correlation is weak due to the intense energy dissipation before desorption. An explanation is given for the misuse of the detailed balance principle in non-equilibrium desorption.

Electromagnetic wave (EMW)-absorbing materials have received significant attention in recent years owing to their important role in mitigating electromagnetic pollution caused by the increased use of wireless communication devices. SiC is expected to be one of the EMW absorbers because of its excellent properties such as chemical stability, mechanical stability, and high hardness; however, SiC alone does not have high EMW absorption performance. SiC-carbon composites were prepared as high-performance EMW-absorbing materials by thermal decomposition of 6H-SiC(0001) substrates. The surface morphology and chemical composition of the pure and annealed samples were evaluated using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Carbon clusters with sizes of several micrometers were formed on the SiC surface after annealing, which formed in an interfacial structure between SiC and carbon and also increased the surface area of carbon. These microstructural changes improved the electromagnetic absorption of the SiC-carbon composite, which was confirmed by transmission attenuation measurements.

Silica (SiO₂)-aromatic polyamide (APA) composite particles with a core-shell structure were synthesized in a single-step process by reacting a diacid chloride monomer with a diamine monomer in a mixture of acetone and N,N-dimethylacetamide in the presence of porous SiO₂ particles. This material was generated without any aggregation between the particles or the presence of APA agglomerates, achieved by optimizing the composition of the reaction solvent. The APA shells were estimated to have thicknesses on the order of several hundred nanometers and comprised 12 wt% of the total composite particle mass. The formation of these APA shells decreased the total pore volume and the surface area of the SiO₂ particles while maintaining the original porous structure. The pore diameters and specific surface areas of both the SiO₂ particles and the composite particles were found to vary when assessed in atmospheres composed of gaseous nitrogen, water, or toluene. These composite particles exhibited a high capacity for dye adsorption, which varied with the specific dye being adsorbed. The extent of dye adsorption was also closely related to the proportion of APA in the composite.

Scanning atom probe has an extraction electrode that localizes an electric field around the sample tip apex, and the ions evaporated by the strong electric field generated by the electrode are sequentially analyzed by the time-of-flight method. By using polyethylene glycol as the matrix, it was confirmed that various target substances supported on tungsten tip can be analyzed. The coordination bond of the 2,2′-bipyridine ligand to iron(II) ion was as stable as that of the 1,10-phenanthroline ligand since the metal complex ions were detected without dissociation while retaining the number of ligands. The copper chelate complex was detected also retaining the bidentate ligand 1,10-phen without releasing any of the ligands. To optimize the calculation parameters, the standard sample containing alkali metals (Na, K, Cs) as mass reference was also established. The newly determined parameters improve the deviation from the reference value (Δm) in the range of m/z = 140–300 Da.

Current measures to prevent viral infections use disinfectants that are highly irritating to the skin and cause health problems such as alcohol-induced hypersensitivity. Therefore, a demand for safer disinfectants exists. ε-Poly-L-lysine (polylysine, EPL) has been used as a food preservative for many years because of its safety and antibacterial properties. In recent years, we developed an antiviral agent consisting only of food additives containing EPL. Studies on feline calicivirus, a norovirus substitute, have shown that serine proteases decompose the protein structure of the outer shell of this virus. The combination of serine proteases and EPL further enhanced the virucidal effects of serine proteases like subtilisin. Investigations of the antiviral effects of this combination revealed its inhibitory effects on enveloped viruses, such as the influenza A virus, but not on non-enveloped viruses. To confirm the damage to viruses, whose infectivity was inhibited by the combined treatment with serine proteases and EPL, morphological changes in virus particles after treatment were observed using transmission electron microscopy. Following the treatment with serine proteases or EPL, the outer shells of the examined viruses were damaged. As the outer shell contributes to the infection of host cells, this morphological alteration might be responsible for the reduced infectivity of these viruses after the combination treatment with serine proteases and EPL.

We found a novel ion-induced domain formation phenomenon in a lipid bilayer membrane of asolectin, a crudely extracted phospholipid mixture from soybean. Asolectin is widely used in cell-free synthesis systems and functional analyses of membrane proteins, therefore we aimed to prepare supported lipid bilayers (SLBs) of asolectin with good reproducibility and to verify their structure and properties. A homogeneous asolectin SLB was formed on a mica substrate in a buffer solution containing K⁺ and lipid domains were generated by substituting K⁺ in the aqueous phase with Na⁺. The domains expanded in the presence of Ca²⁺ and disappeared in the K⁺-containing buffer in a nearly reversible manner. The lipid domain induced by a monovalent cation is a unique phenomenon. We proposed that the effect of Ca²⁺ is due to the bridging effect of the divalent cation between negatively charged PI molecules. These results provide new insights into the lateral organization within bilayer membranes of naturally derived lipids.

Insulator–metal phase transition in vanadium dioxide (VO₂) is influenced by nanoscale morphology and defects. To gain in-depth understanding of its microscopic mechanism, it is crucial to directly characterize the correlation between structural features and phase transition behavior. In this study, we grow VO₂ thin films on TiO₂(110) substrates using pulsed laser deposition and investigated their phase transition using X-ray diffraction (XRD), Raman spectroscopy, and scattering-type scanning near-field optical microscopy (s-SNOM). The phase transition is confirmed by a temperature-dependent XRD measurement, indicating the structural transition from the monoclinic (insulator) to the rutile (metal) phase. Additionally, using infrared s-SNOM, we directly observe the individual anisotropic nanodomain in the VO₂ thin film, enabling the visualization of the insulating and metallic phases based on the contrast in the s-SNOM contrast at the nanoscale. Our results reveal that metallic nanodomains nucleate and spread in a spatially inhomogeneous manner, strongly influenced by grain width and lattice strain along the [001] direction.

Indium (In)-doped ZnO thin films were deposited on glass substrates via radio frequency reactive magnetron sputtering at substrate temperature at 180, 200, 225, and 250°C. X-ray diffraction data shows In-doped ZnO samples displayed the hexagonal wurtzite structure typical of ZnO. Atomic force microscopy indicates the surface roughness enhance when increasing the growth temperatures. Ultraviolet-visible transmission spectroscopy of In-doped ZnO thin films exhibited over 80% transmittance in the visible region. Additionally, the optical bandgap ranges from 3.23 to 3.41 eV and tends to widen with increasing the growth temperature. The Hall effect measurements reveal that a carrier concentration exceeding 10²¹ cm⁻³ and a resistivity of approximately 10⁻⁴ Ω cm. Furthermore, the Seebeck coefficient of the In-doped ZnO thin films ranges from 23.15 to 32.7 µV K⁻¹, with a power factor between 3.23 and 247.02 µW m⁻¹ K⁻². Our results highlight the important role of substrate temperature in controlling the morphological, structural, optical, electrical, and thermoelectrical characteristics of In-doped ZnO thin films, which may lead to the material’s optimization for modern technological applications.

The relationship between oxidation-treated copper alloy (brass) and its color tone was investigated. The results showed that the color change of the copper alloy due to oxidation treatment was attributed to changes in surface morphology caused by dezincification, which led to a decrease in the L* value, which indicates the brightness or darkness of a color. Furthermore, copper hydroxide formed during the initial stage of treatment transitioned to copper oxide over time. This transition influenced the b* value, which represents the blue-yellow axis of a color, suggesting that the color tone can be controlled by adjusting the ratio of hydroxide to oxide.

The search for new materials with unique properties is crucial for various applications, especially in biomedical fields such as drug delivery. Carbon fullerene molecules, consisting of 20 to 70 atoms [C_p (p = 20, ⋯, 70)], have significant potential and have been extensively studied for their biomedical applications. Fullerene is an allotrope of graphene with a special structure capable of encapsulating drugs. This research aims to predict the partition coefficient (LogP) of fullerene, which describes the ratio of a compound's concentration in octanol to that in water and is a critical parameter for identifying potential drug candidates. The research also aims to evaluate its suitability for future applications. Computational tools were employed to predict the LogP value of C_p (p = 20, ⋯, 70) fullerene molecules. The study focused on fullerene with 60 carbon atoms (C₆₀), which was optimized at the B3LYP/6-31G(d) level. The molecule was then incorporated into a molecular dynamics model to investigate the hydrate shell. The hydrate shell of fullerene in water was analysed using the radial distribution function. The AMBER software was utilized to study the ability of water molecules to form a solvation shell around the fullerene molecule. The results suggest that fullerene (C₆₀) requires specific modifications to enhance its usability and reduce its LogP for effective drug delivery. However, the molecular simulation provides detailed insights into the solvation shell of fullerene, showing that the fullerene-water system, under certain conditions, can exist as a stable dispersion suitable for drug delivery purposes like an oil in water system.

High temperature waste heat recovery remains a major challenge in the development of thermoelectric materials, particularly for applications close to 700°C. Although techniques for measuring the physical properties of thermoelectric materials have advanced, accurate evaluation of the correlation between physical properties and structural changes at high temperatures remains difficult due to the structural transformations that occur under such conditions. Especially, local structural analysis using X-ray absorption fine structure (XAFS) faces significant challenges in high temperature environments due to the need to withstand extreme thermal conditions. In this study we have addressed these challenges by developing a vacuum heating apparatus capable of performing XAFS measurements at temperatures up to 700°C. This apparatus uses Kapton film as the window material, chosen for its excellent heat resistance and X-ray transmittance. Using this system, we successfully measured the Fe K-edge XAFS spectra of a test material from room temperature to 700°C. In addition, to investigate the changes in the chemical state of Fe under different heating environments, measurements were performed under atmospheric heating conditions. Radial structural function analysis of the obtained spectra using Athena revealed that weathered biotite exhibits excellent structural stability at high temperatures up to 700°C, while the interaction between Fe and oxygen is strongly influenced by the surrounding environment. Moreover, detailed pre edge analysis suggested a partial increase in Fe³⁺ content after heating, especially under atmospheric conditions, implying the possible oxidation of Fe during the cooling process. This study has demonstrated the suitability of this system for high temperature structural analysis. The results highlight the potential of this apparatus to overcome technical barriers associated with high temperature XAFS measurements and provide a platform for detailed investigations of structural changes in various materials under extreme thermal conditions. This work represents a significant advance in the development of instrumentation for high temperature research and contributes to the advancement of thermoelectric materials research.

High intensity accelerator-driven neutron sources with a free surface liquid lithium (Li) target system are widely being designed and developed because heat dissipation under high beam power is easier compared to a solid target and there is no need to periodically replace the target. However, a linear accelerator must be operated under ultra-high vacuum (<10⁻⁵ Pa) to avoid beam loss with the residual gas and keep the designed performance. On the other hand, a liquid Li target system should be handled under much lower vacuum (>10⁻³ Pa) to avoid Li boiling. Therefore, the experimental verification of outgas rate, residual gas type and Li vapor behavior are required for individual condition of operational temperature and flow velocity of the liquid Li. We assembled a 1/10 scale experimental setup of the high energy beam transport section of the advanced fusion neutron source accelerator and demonstrated the design with a liquid Li loop system. Although the outgassing was higher than expected, differential pumping of 10⁻⁴ and 10⁻² Pa was experimentally demonstrated under Li flow. The total Li vapor contamination in this experimental setup is estimated to be a few grams a year. The results will be useful for designing the high intensity accelerator-driven neutron sources with a windowless liquid Li target system.

To elucidate the effect of medium strain on silicon (Si) transport in Si oxides, first-principles calculations were employed to evaluate the variation in the diffusion barrier of excess Si in isotropically strained quartz. Our results reveal that the barrier height exhibits significant dependence on density. The optimal barrier height, determined from the most stable metastable structure and the lowest transition state structure, was found to be 5.06 eV, in excellent agreement with the experimental value of 5.13 eV. Furthermore, a detailed analysis of experimental Si diffusion coefficients suggests that oxide films used in experiments can be categorized into at least two distinct types. This finding underscores the necessity of classifying oxide films based on structural characteristics rather than treating them as a single amorphous phase, ensuring a more precise understanding of their quality.

In this study, ion irradiation induced microstructural development of polycrystalline double-thick-walled (DTW) silicon carbide (SiC) nanotubes are investigated. In-situ transmission electron microscopy (TEM) observations of two kinds of polycrystalline DTW SiC nanotubes with a wide and narrow spacing between the outer and inner nanotubes are carried out under the ion irradiation with 200-keV Si⁺ ions at room temperature. The critical doses of amorphization for both DTW SiC nanotubes are larger than those of SiC bulk materials in the previous studies. Amorphous DTW SiC nanotubes are successfully synthesized for the first time via the ion irradiation of both polycrystalline DTW SiC nanotubes. From in-situ TEM observation results, all of outer, inner diameters and length of both inner and outer nanotubes increase with increasing the irradiation dose till around complete amorphization of SiC crystals, and then decrease. After ion irradiation of more than 20 displacement per atom, polycrystalline DTW SiC nanotubes with a wide and narrow spacing between the outer and inner nanotubes are transformed to amorphous SiC nanotube and SiC nanowire, respectively.