National Institutes for Quantum and Radiological Science and Technology
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Long functional graft polymer induced multiscale morphological inversion and enhanced anion transport efficiency in radiation-grafted anion exchange membranes
No full textWe comprehensively investigate the hierarchical structures of the previously reported radiation-grafted anion-exchange membranes (AEMs), consisting of p-(2-imidazoliumyl) styrene graft-polymers onto poly(ethylene-co-tetrafluoloethylene) (ETFE) films with different grafting degree (GD), using the partial scattering function (PSF) analysis. We first confirm the existence of a characteristic GD (GDc) of 20?25%, over which AEMs show enhanced anion transport efficiency. To clarify the structure features in correlation with GDc, two AEMs with GD of 14% and 42% (AEM14 and AEM42) are selected for PSF analysis, where AEMs are treated as a 3-component system, containing EFTE base polymer (BP), graft polymer (GP) and water (W). Our results reveal the two different microphase inversions across GDc in tens of nanometer and a few nanometer ranges, respectively. In the large scale (> 10 nm), at GD GDc (i.e., AEM42), a network structure is formed by irregularly shaped BP domains with a radius of gyration of ~9.5 nm dispersing in GP/W matrix (hydrophilic/hydrophobic phase-inversion compared to AEM14). In small scale ( 42%.journal articl
Development of a new tool to simultaneously measure soil-gas permeability and CO2 concentration as important parameters for geogenic radon potential assessment
No full textThis study assessed the geogenic radon potential using PECAME, an innovative tool designed to simultaneously measure soil-gas permeability and CO concentration ? two key parameters for understanding radon transport in soil. Comparative field studies using the RADON-JOK device in various geological settings in Japan and Poland demonstrate the effectiveness of PECAME. These studies reveal a strong correlation between PECAME and RADON-JOK, with an R value of 0.94 for flow rate of 3.5 dm min. Since the soil-gas Rn concentration and permeability were measured simultaneously, the geogenic radon potential was calculated. Most measured points fall within the low to medium radon index zones, with two exceptions near active faults located in the high zone. Therefore, permeability and CO measurements using PECAME may facilitate further research in Japan to develop a comprehensive geogenic radon potential map.journal articl
High-Energy X-ray Dynamics of the Recovery and Recrystallization Behaviors of Steels Subjected to Uniaxial Hot Compression and Isothermal Annealing
No full textNi-30 mass%Fe オーステナイト合金について、一軸圧縮加熱下と等温熱処理中の微細構造の変化を角度分散放射光X線回折測定法によりその場観察した。この合金中のγ相の圧縮加熱下と等温処理における転位密度の変化は、Fe-0.2 mass%Cの結果とよく一致した。組織は主に転位密度の高い粗大な結晶粒から構成されていたが、加工硬化に起因する動的再結晶が750℃で発生した。再結晶速度は等温熱処理時間によって変化し、転位密度を静的回復と回復/再結晶に分類することができた。結晶方位の分布の変化から推定した再結晶の活性化エネルギーは約280kJ/molであり、純Ni金属と同程度であった。これらの結果は、低炭素鋼の高温γ相における回復・再結晶挙動に関する包括的な知見を提供するものである。journal articl
Neurobiology of COVID-19-Associated Psychosis/Schizophrenia: Implication of Epidermal Growth Factor Receptor Signaling
No full textCOVID-19 exhibits not only respiratory symptoms but also neurological/psychiatric symptoms rarely including delirium/psychosis. Pathological studies on COVID-19 provide evidence that the cytokine storm, in particular (epidermal growth factor) EGF receptor (EGFR, ErbB1, Her1) activation, plays a central role in the progression of viral replication and lung fibrosis. Of note, SARS-CoV-2 virus (specifically, S1 spike domain) mimics EGF and directly transactivates EGFR, preceding the inflammatory process. In agreement, the anticancer drugs targeting EGFR such as Nimotuzumab and tyrosine kinase inhibitors are markedly effective on COVID-19. However, these data might raise a provisional caution regarding implication of psychiatric disorder such as schizophrenia. The author's group has been investigating the etiologic and neuropathologic associations of EGFR signaling with schizophrenia. There are significant molecular associations between schizophrenia and EGFR ligand levels in blood as well as in the brain. In addition, perinatal challenges of EGFR ligands and intraventricular administration of EGF to rodents and monkeys both resulted in severe behavioral and/or electroencephalographic endophenotypes relevant to this disorder. These animal models also display postpubertal abnormality in soliloquy-like self-vocalization as well as in intercortical functional connectivity. Here, we discuss neuropsychiatric implication of coronavirus infection and its interaction with the EGFR system, by searching related literatures in PubMed database as of the end of 2023.journal articl
Non-destructive measurement of the charge transfer across LaMnO3/SrTiO3 interfaces
No full textLocal polarization and charge transfer at the interface between 7-unit cell-thick LaMnO3 (LMO) ultrathin films and substrates composed of Nb-doped (0.05 wt. %) and undoped SrTiO3 (STO) are examined by resonant surface x-ray diffraction. Notably, this photon-in photon-out technique allows us to simultaneously examine the valence distribution and local polarization with minimal radiation damage. Consistent with previous reports, Mn2t is observed at the interface. Furthermore, the degree of charge transfer is nearly unchanged by the 0.05 wt. % of Nb doping. In the middle of the LMO films, the valence of Mn is 3t. Local polarization estimated from the cation/anion displacements shows that the electric field points outward in the LMO films, and polarization is suppressed in the STO substrate region.journal articl
Impact of confounding by smoking on cancer risk estimates in cohort studies of radiation workers: a simulation study
No full textPrevious studies on cohorts of radiation workers have provided valuable insights into the effects of low-dose-rate radiation; however, some concerns regarding the potential confounding effects of smoking have been expressed. Although some studies have collected smoking data and adjusted for this variable, their limited numbers and the presence of other confounders obscure the extent of the impact of smoking on their results. To address this, we conducted a simulation study to quantitatively evaluate the bias from confounding and modeling conditions, similar to actual epidemiological studies. Our analysis, based on data from Japanese radiation workers, indicated that not adjusting for smoking can lead to an overestimation of radiation effects by approximately 110%. This overestimation was relatively insensitive to sample size and dose distribution parameters, but varied with radiation and smoking risk, baseline smoking probability, and heterogeneity in baseline risk. Considering the simplified settings of this simulation study and the uncertainty of the estimates of Japanese radiation workers, our simulation results were consistent with those of the real-world epidemiological study. We also compared the results using Cox and Poisson regression models, ensuring that their modeling approaches were as similar as possible, and found minimal differences between them.journal articl
Improvement of core plasma power and current balance models for tokamak systems code considering H-mode plasma profiles
No full textWe propose the models for the systems codes to calculate the bootstrap current fraction, neutral beam-driven current, and synchrotron radiation loss power, considering the plasma profiles with the H-mode pedestals. The scaling formulae of the bootstrap current fraction are developed for the parabolic and H-mode plasma profiles by fitting the data prepared using a magnetohydrodynamic equilibrium calculation code including a detailed model of the bootstrap current. The developed simple model of the neutral beam-driven current is applicable to arbitrary plasma profiles and shapes. We show the geometric approximation of the flux surface averaged magnetic field strength, plasma surface area, and plasma volume to calculate the synchrotron radiation loss power using the CYTRAN module with only the parameters used in the systems codes. The validity of these models is confirmed by comparing the results to those calculated by the detailed models. These models enable the systems codes to consistently consider the plasma profiles with the pedestals in the core plasma power and current balances because the other quantities in the balance equations can be evaluated by calculating the profiles of the quantities and integrating them numerically within computing time acceptable for the systems analysis.journal articl
Two-color CO2 laser long-distance interference measurements with long-time stabilization in JT-60SA
No full textWehave developed a two-color CO2 laser interferometer in JT-60SA, which features a long transmission line and a long-time stabilization
system. We inject two laser beams with an optimized beam size into the plasma of JT-60SA. A newly developed beam axis stabilizing system
stabilizes the laser beam line to the plasma, which constitutes one fourth of the total line length of 214 m, for more than 11 hours, ensuring
no beam line loss during the integrated commissioning phase of JT-60SA. It is possible to measure the line-integrated electron densities of
JT-60SA plasmas with a resolution of 2 × 10^19 m^?2. The typical NeL = 1.4 × 10^20 m^?2. Experimental evidence also demonstrates the challenge
of compensating for line-integrated electron density errors, even with a two-color interferometer.journal articl
Structures of Polyhydroxyalkanoate Synthase PhaC from Aeromonas caviae, Producing Biodegradable Plastics.
No full textPolyhydroxyalkanoate (PHA) is a biodegradable polyester that can serve as a promising alternative to petrochemical plastics which present a serious source of pollution. PHA synthase (PhaC) is a key enzyme responsible for producing a wide variety of PHAs in microorganisms. Here we present crystal structures of full-length PhaC from?Aeromonas caviae, a high-performance PhaC employed for industrial use. The structure reveals an N-terminal helical domain that mediates head-to-head dimerization and stabilizes the C-terminal α/β catalytic domain to form a tunnel that connects the catalytic center embedded inside the protein to the protein surface. We showed that this tunnel is a putative egress tunnel for the product PHA chain. Our results establish a fundamental understanding of the PhaC machinery that should lead to improvement of this enzyme in industrial applications.journal articl
Identifying parasitic oscillations at 570 and 600 MHz in a 170-GHz gyrotron collector
No full textParasitic oscillations cause undesirable electromagnetic wave emissions from gyrotrons. In a recent study using a 170-GHz gyrotron, waves with a frequency of approximately 570 MHz were observed, which potentially indicated the occurrence of parasitic oscillations in the gyrotron. However, the site of this excitation was not likely at well known gyrotron components such as the beam tunnel and cathode. This study examined parasitic oscillations in a 170-GHz gyrotron to identify the site of their excitation. Frequency measurements showed that waves with a frequency of approximately 570 and 600 MHz were generated. In addition, the wave excitations were observed only at certain collector coil currents, potentially indicating that the parasitic oscillations were excited at the collector. Therefore, resonance frequencies around the collector (including window and DC break sections) were calculated and measured. The calculated and measured resonant frequencies were consistent with the frequencies of the parasitic oscillations. Thus, this study determined that the parasitic oscillations were excited at the collector and the resonance frequencies were determined by the inner shape around the collector. The findings of this study enhance the understanding of unintended wave-generation mechanisms in high-power gyrotrons, which is essential for improving their operational reliability.journal articl