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A pilot study was carried out to measure indoor radon concentrations in a uranium mining area of northern Kazakstan. A total of 80 places at kindergartens, elementary schools, and dwellings were selected in Aqsu village and Astana city as the uranium mining area and background area for comparison, respectively. In Astana and Aqsu, the 3-month radon concentrations from late summer to autumn in 2022 were measured using the RADUET passive radon detectors. Radon concentrations ranged from 4 to >2,000 Bq m−3 (mean ± standard deviation: 290 ± 173 Bq m−3) throughout the study areas. The concentrations were higher in Aqsu, and 70% of the dwellings there exceeded 300 Bq m−3, whereas only 5% of them exceeded 300 Bq m−3 in Astana. Accordingly, the new dose conversion factor for radon recommended by ICRP Publication 137 was applied to calculate the annual effective dose. The annual effective dose from the inhalation of radon was estimated to be 3.6 ± 4.6 mSv y−1 for Astana and 23.7 ± 15.6 mSv y−1, for Aqsu, which are both higher than the world average value of 2.5 mSv y−1.

Boron-induced electronic states of antiperovskite nitrides such as ferrimagnetic Mn4N were investigated via a combination of polar magneto-optical Kerr effect (p-MOKE) spectroscopy and spectroscopic ellipsometry (SE). The boron content in the Mn4N film varied from 0 to 4.3 at.%, for which the crystal structure was maintained. The amplitude of p-MOKE spectra and the diagonal and off-diagonal dielectric tensors decreased with increasing boron content, which is in agreement with magnetic properties such as magnetic anisotropy and saturation magnetization. These results were related to the lattice expansion and displacement of the charge density in Mn4N by boron doping. However, the peak energy of Lorentz oscillator in the diagonal elements of dielectric tensors suggests that a dominant inter-band transition was independent of boron content.

The behavior of the partial pressure of SiF4, a byproduct of fluorine-based plasma etching, has been measured in real-time using a method based on Laser Absorption Spectroscopy (LAS). The partial pressure of SiF4 is highly correlated with the etch rate of SiO2 (R 2 = 0.999). Etch endpoints were clearly observed from the signal transitions, whose period indicate the etch rate uniformity. In addition, integrating the partial pressure of SiF4 with respect to time is correlated with the number of Si atoms etched regardless of the composition of the etched materials. Specifically, Si, SiO2 and Si3N4 were examined in this work. Based on the strong relationship between the measured SiF4 partial pressure and the etching profiles, real-time monitoring by LAS is useful for the prediction of etch profiles.

High uniformity of the thickness and net donor concentrations (N d-N a) in 100 mm diameter β-Ga2O3 (001) epitaxial wafer prepared by halide vapor phase epitaxy was demonstrated. An epitaxial wafer grown on a substrate with a miscut angle near 0° generated a specific epitaxial region with a lower growth rate and a higher N d-N a than the rest of the region, which deteriorated the wafer uniformity. In contrast, epitaxial wafers prepared on substrates with a miscut angle of –0.1° suppressed the occurrence of the specific epitaxial region, and an average thickness after chemical mechanical polishing of 10.6 μm with 5% tolerance and an average N d-N a without intentionally doping of 1.1 × 1016 cm−3 within 7% tolerance were successfully obtained.

One promising way to reduce the use of noble metal catalysts is to use extremely fine particle catalysts, such as subnanoclusters and single-atom catalysts. For practical use, suppression of diffusion and agglomeration of catalysts are needed. Heteroatom-doped graphene, which has high specific surface area, high chemical and mechanical stabilities, high electrical and thermal conductivities, and contains anchoring sites for catalysts, is promising catalyst support. Heteroatom-doped graphene can widely control the support effects. This review summarizes recent dopant structure characterization using spectroscopy and density functional theory calculations. The distribution of highly-dispersed metal catalysts and their diffusion properties are discussed. In addition, The effects of environmental conditions on catalyst dynamic behaviors are introduced. Finally, the outlook of heteroatom-doped graphene and new two-dimensional material supports is discussed.

Hexagonal rare-earth manganese oxide YMnO3 thin films were prepared on yttria-stabilized zirconia (111) substrates by metal organic decomposition method. The crystallinity and morphology of YMnO3 thin films crystallized at various temperatures were examined by X-ray diffraction and atomic force microscopy measurements, respectively. Single phase YMnO3 was obtained for the sample prepared by annealing temperatures of 950 °C. AFM analysis revealed that a smooth surface with a roughness of 0.15 nm was achieved for YMnO3 thin film annealed at 950 °C and 1000 °C, while three-dimensional growth for other samples prepared at 750–900 °C, 1050 °C, and 1100 °C. A narrow band at 1.6 eV and a broad band at 5 eV due to electronic transitions in the manganese and oxygen bands were observed in an absorption spectrum.

Lead-free ferroelectric and piezoelectric ceramics, (Bi0.5Na0.5)TiO3 [BNT] ceramics were prepared by controlling the quenching rate. The quenching effects mainly caused an increase in lattice distortion 90-α and T d, contribution of electrical properties and ordered structural phase transitions. In this study, we analyzed oxygen tracer diffusion and examined domain structures for quenched BNT ceramics, and then we proposed a mechanism for the quenching effect. As a result, the diffusion coefficients D of 18O tracer for the OF and quenched samples were 2.5 × 10–11 and 1.8 × 10–11 cm2 s−1, respectively, and there were no significant differences in oxygen vacancies after quenching. The correlation between the quenching effect and oxygen vacancies was also examined in BNT with hard and soft dopants. However, the contribution of oxygen vacancies was small thus, the correlation between the quench effect and oxygen vacancies was low. On the other hand, the domain structure of BNT ceramics was observed and the domain size of OF-BNT was around 20 nm. This is a typical domain size for BNT ceramics. In contrast, the domain size of the quenched BNT was 40 nm. Thus, quenching increased the domain size and decreased their density. Consequently, we propose that the domain structure is strongly correlated with the quench-induced increase in lattice distortion and T d, its contribution to electrical properties, and ordered structural phase transitions.

GaN layers are grown on 2 inch ScAlMgO4 (0001) nominally on-axis substrates by metalorganic vapor phase epitaxy. The epilayer structural qualities are comparable to those of conventional GaN on sapphire (0001) substrates. The wafer curvature is investigated using X-ray diffraction, and the results suggest suppressed bowing in the GaN/ScAlMgO4 heterostructures compared with the GaN/sapphire heterostructures. This result is attributed to a smaller mismatch of the thermal expansion coefficients in GaN/ScAlMgO4. The suppressed bowing can be beneficial for device processes.

We address effects of spin-orbit coupling (SOC), phenomenologically added to a two-component Bose-Einstein condensate composed of particles moving by Levy flights, in one- and two-dimensional (1D and 2D) settings. The corresponding system of coupled Gross-Pitaevskii equations includes fractional kinetic-energy operators, characterized by the Levy index, \alpha < 2 (the normal kinetic energy corresponds to \alpha = 2). The SOC terms, with strength \lambda, produce strong effects in the 2D case: they create families of stable solitons of the semi-vortex (SV) and mixed-mode (MM) types in the interval of 1 < \alpha < 2, where the supercritical collapse does not admit the existence of stable solitons in the absence of the SOC. At \lambda --> 0, amplitudes of these solitons vanish as (\lambda)^{1/(\alpha - 1)}., Comment: to be published in Journal of Physics B: Atomic, Molecular, and Optical Physics

In ocean-based renewable energies, such as wave motion, ocean current, tidal current and ocean thermal energy, many studies have been conducted on the wave energy conversion system and they have been tested in many countries. In this study, a tidal current energy is focused. Collecting a tidal flow is very important because it is generally known that a power available from a stream of water is proportional to the cube of the free stream velocity of the current. In this research, a bi-directional turbine system is investigated for a tidal flow that changes the direction periodically. Numerical investigations are conducted on a bi-directional flow collector with guide vane to collect the flow, in which the effects of vane skew angle and blade number are investigated. Calculated results showed that the collector with eight guide vanes was the highest angular moment at turbine inlet. The axial velocity at turbine inlet was larger for smaller value of the vane skew angle, whereas the tangential velocity at the turbine inlet was larger for larger value of the vane skew angle. As the results of both the profiles of axial and tangential velocity, the angular moment took the local maximum value at around the angle of 180 deg. in this study.

Plumose pattern often appears on the fracture surface of drying pastes. We show a few experimental results of the crack propagation in the drying pastes. We find that the crack propagation sometimes exhibits jump motions. We have also performed an experiment of the crack propagation in a tilted container where the crack propagates from the deeper to shallower sides. This experimental result suggests the importance of the movement of water content. We propose a simple coupled map lattice model. In the numerical simulation, a plumose-like pattern appears owing to the instability of the flat surface of the fracture. The numerical simulation reproduces the jump motions in the crack propagation. We have performed another experiment where a vertical streak pattern appears when the crack propagates downward by cutting into the top surface of the drying paste.

This study investigates the possibility of hydrogen migration in BaTiO3-based dielectrics to improve the electrical reliability of multi-layer ceramic capacitors under conditions of high temperature, humidity, and electric field bias. It was observed that the deuterium in the dielectric drifted and migrated with the electric field, suggesting that deuterium exists as D+. The activation energy was found to be 0.34 eV, which is lower than that observed in previous studies. This finding offers a better understanding of the mechanism behind the migration of deuterium in a dielectric, which is highly relevant to future research in dielectrics and electronic components.

It is known that the interplay of the spin-orbit-coupling (SOC) and mean-field self-attraction creates stable two-dimensional (2D) solitons (ground states) in spinor Bose-Einstein condensates. However, SOC destroys the system's Galilean invariance, therefore moving solitons exist only in a narrow interval of velocities, outside of which the solitons suffer delocalization. We demonstrate that the application of a relatively weak moving optical lattice (OL), with the 2D or quasi-1D structure, makes it possible to greatly expand the velocity interval for stable motion of the solitons. The stability domain in the system's parameter space is identified by means of numerical methods. In particular, the quasi-1D OL produces a stronger stabilizing effect than its full 2D counterpart. Some features of the domain are explained analytically., Comment: to be published in Journal of Physics B: At. Mol. Opt. Phys

The elastic scattering process for the nuclear reactions induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target was measured for the first time in the energy range around the Coulomb barrier. Extensive theoretical calculations within the framework of the optical model were performed. An excellent agreement between experimental data and theoretical predictions was achieved for the reaction 7Be + 208Pb, while a comprehensive understanding of the reaction dynamics induced by the more exotic projectile 8B is still far to be reached. Predictions of the cross section for the breakup for both systems will also be given., The 8B experiment was performed at RI Beam Factory operated by RIKEN Nishina Center and CNS, University of Tokyo. This work was supported by the Polish National Science Centre under Contract No. 2014/14/M/ST2/00738 (COPIN-INFN Collaboration), by JSPS KAKENHI (Nos. 16K05369, and 19K03883) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan and by the projects: CONACyT LN-294537 and DGAPA-PAPIIT IA103218.

Tissue engineering has attracted attention worldwide because of its application in regenerative medicine, drug screening, and cultured meat. Numerous biofabrication techniques for producing tissues have been developed, including various scaffold and printing methods. Here, we have proposed a novel tissue engineering method using a net metal mould without the use of a scaffold. Briefly, normal human dermal fibroblasts seeded on a dimple plate were subjected to static culture technique for several days to form spheroids. Spheroids of diameter ⩾200 μm were poured into a net-shaped mould of gap ⩽100 μm and subjected to shake-cultivation for several weeks, facilitating their fusion to form a three-dimensional (3D) tissue. Through this study, we successfully constructed a scaffold-free 3D tissue having strength that can be easily manipulated, which was difficult to construct using conventional tissue engineering methods. We also investigated the viability of the 3D tissue and found that the condition of the tissues was completely different depending on the culture media used. Collectively, this method allows scaffold-free culture of 3D tissues of unprecedented thickness, and may contribute largely to next-generation tissue engineering products.