National Institutes for Quantum and Radiological Science and Technology
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Development of high energy resolution crystal analyzer based on microporous ceramics for resonant inelastic X-ray scattering program at HEPS
No full textThe spherically bent X-ray crystal analyzer (SBCA) is one of the key optical elements for performing high energy resolution hard X-ray spectroscopies based on Rowland circle geometry. To meet the requirements of Resonant Inelastic X-ray Scattering (RIXS) program at High Energy Photon Source (HEPS), the fourth-generation high energy synchrotron in Beijing, China, high energy resolution crystal analyzers were fabricated. The fabrication processes of vacuum-mounted flat-diced crystal analyzers using home-designed devices with microporous ceramics are presented. The energy resolution of the vacuum-mounted crystal analyzers, for measuring Cu K-edge and Re L3-edge RIXS, are bench marked with that of the glued flat-diced crystal analyzers. The gluing and vacuum-mounted analyzers are proven to be reliable techniques for the routine production of spherical bent diced crystal analyzers with energy resolution in the order of tens of milli-electron volts, and with good focal properties and efficiency. In particular, the vacuum-mounted technique will be beneficial for the RIXS techniques to target element of interests.journal articl
Electronic structure and resonant inelastic x-ray scattering in Ta2NiSe5
No full textWe study the electronic structure of Ta2NiSe5 in its low-temperature semiconducting phase, using resonant inelastic x-ray scattering (RIXS) at the Ta L3 edge. We also investigate the electronic properties of Ta2NiSe5 within the density-functional theory (DFT) using the generalized gradient approximation in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. While ARPES, dc transport, and optical measurements indicate that Ta2NiSe5 is a small band-gap semiconductor, DFT gives a metallic nonmagnetic solution in Ta2NiSe5. To obtain the semiconducting ground state in Ta2NiSe5 we use a self-interaction-like correction procedure by introducing an orbital-dependent potential Vl into the Hamiltonian. We investigate theoretically the x-ray absorption spectroscopy and RIXS spectra at the Ni and Ta L3 edges and analyze the spectra in terms of interband transitions. We also investigate the RIXS spectra as a function of momentum transfer vector Q and incident photon energy.journal articl
Excitation of the isoscalar giant monopole resonance using 6Li inelastic scattering
No full textThe incompressibility of infinite nuclear matter (K_{infty}) is a parameter in the description of the nuclear equation of state that governs the energy cost associated with density oscillations near the saturation density. The most direct proxy for studying this property of infinite nuclear matter is to probe the isoscalar giant monopole resonance (ISGMR) in finite nuclei. This work explores the use of 6Li as a probe to study the ISGMR in several stable nuclei: 58Ni, 90Zr, 116Sn, and 208Pb, as complementary to using inelastic scattering of \alpha-particles, which has been used to great effect over the last several decades. Elastic and inelastic scattering data for these targets were collected with 343-MeV 6Li beams. In all nuclei studied in this work, the ISGMR strength distributions extracted from multipole decomposition analyses of the inelastic scattering spectra agree very well with the previously measured ISGMR responses from \alpha-particle scattering, establishing the feasibility of employing 6Li inelastic scattering in the investigation of the ISGMR.journal articl
Time?lapse imaging of cells in spatially fractionated X?ray fields using a mini beam as an alternative to accelerator?based microbeams
No full textDue to the small number of accelerator?based X?ray microbeam facilities in the world, their use for biological research purposes is limited. Thus, the development of alternative methods is of high importance for the understanding of X?ray microbeam radiation biology expansion and its future utility. In this study, we performed mini beam irradiation of cells using a lead (Pb) collimator as an alternative method to microbeams. Also, we employed human cervical carcinoma HeLa cells and hTERT?immortalized fibroblast BJ?1 cells that express fluorescence ubiquitination?based cell?cycle indicators (FUCCI). FUCCI labeling was useful in distinguishing irradiated from non?irradiated cells in the case of HeLa cells. Our imaging results clearly showed differences in the behavior of HeLa and BJ-1 cells in spatially heterogeneous radiation fields; in the case of HeLa cells, G2/M phase arrest cells in the cell population were clearly observed. The Pb sub?milli?collimators are a promising alternative to X?ray microbeams for radiobiology studies, and their combination with time?lapse imaging is a possible approach for investigating tissue responses in spatially non?uniform radiation fields.journal articl
Depth-resolved measurements of magnetic domains in grain-oriented elect rical steel
No full textObservation of magnetic domains well below thep surface of a thick opaque specimen is fairly difficult because of a lack of adequate experimental techniques. We, therefore, have developed a bulk-sensitive magnetic microscope utilizing a new magnetooptical effect called x-ray magnetic circularly polarized emission before. However, because of the poor spatial resolution of the receiving optics, depth-resolved measurements of magnetic domains could not be performed. In this paper, we propose a new setup for improving the spatial resolution of the receiving optics and actually construct a confocal microscope that can conduct depth-resolved measurements. Several cross-sectional images of magnetic domains of grain-oriented electrical steel are presented to demonstrate the performance of our depth-resolved technique. The spatial resolution of the microscope is also estimated to be approximately 10 μm. Three-dimensional visualization of magnetic domains in electrical steel, for instance, becomes possible utilizing this technique.journal articl
Determination of ultra-trace Pu isotopes in large-volume seawater samples from the South Pacific Ocean using sector field ICP-MS combined with extraction chromatography
No full textThe plutonium (Pu) contamination in the marine environment has raised global concerns over the past 70 years. However, the source and fate of 239+240Pu in the South Pacific seawater are poorly understood because of their relatively low abundance. This study established a sequential separation method, including the Fe(OH)3 primary co-precipitation, CaF2/LaF3 secondary co-precipitation, and TEVA+UTEVA+DGA extraction chromatographic separation to determine the Pu isotopes in the South Pacific seawater by SF-ICP-MS. The method detection limits of 239Pu and 240Pu were 0.004 fg/L (0.008 mBq/m3) and 0.005 fg/L (0.044 mBq/m3) for 100 L seawater, respectively. The chemical separation method and APEX-Q high-efficiency sample introduction system are efficient in removing 238U interferences, with the overall 238U removal efficiency of ~1011 and ~1012 for 239Pu and 240Pu measurements, respectively. This method was validated by the Pu-free seawater spiked with the IAEA-443 seawater reference material. Based on this method, the 239+240Pu activity concentrations in the South Pacific surface seawater were determined, ranging from 0.45±0.01 to 2.07±0.02 mBq/m3, with the 240Pu/239Pu atom ratios between 0.151±0.028 and 0.252±0.031. The two end-member mixing model revealed that the releases from the global fallout contributed more than that of the Pacific Proving Grounds (PPG) to Pu in the South Pacific seawater. The release of Pu isotopes from the French nuclear tests to the South Pacific surface seawater was negligible. Therefore, the established method can be used for the ultra-trace Pu measurements in large-volume seawater samples and the findings strengthen the understanding of Pu behaviors in the South Pacific.journal articl
Microbeam irradiation reveals cytoplasmic damage contributes to micronuclei induction.
No full textMicrobeam technology offers a valuable tool to investigate inter- and intracellular responses to radiation-induced damage. While direct nucleus irradiation is known to be the primary cause of various radiobiological effects, the cytoplasm also receives radiation and potentially influencing intracellular responses. This study aims to determine whether cytoplasmic irradiation contributes to micronuclei induction when the cytoplasm and nucleus are sequentially irradiated.
Microbeam irradiation were performed using the SPICE-QST microbeam at the National Institutes for Quantum Science and Technology, delivering 3.4 MeV protons (LET in water: 11.7 keV/μm) with a 2 μm beam diameter. Three targeted irradiations were employed: (N) nucleus-only, (C) cytoplasm-only, and (N+C) irradiating both the nucleus and cytoplasm. In (N+C), with 1000 protons delivered to the cytoplasm in the N+C group. Immediately post-irradiation, the cyto-block method was employed for micronucleus (MN) formation analysis. Cells were fixed 50 hours later, followed by staining the cytoplasm and nucleus with Cell Tracker Orange (10 μg/ml) and Hoechst33342 (1 μg/ml), respectively. Fluorescence images of over 1000 binucleated cells were captured using the SPICE offline microscopic system.
The MN induction rate per bi-nucleated cell was compared between N and N+C (1000 protons) irradiation. N irradiation displayed a peak MN induction rate at around 100 protons, whereas N+C irradiation peaked at around 300 protons. The result implies that the cytoplasmic irradiation induced protective response against MN induction. Notably, at 1000 protons or more, N+C irradiation yielded an MN induction rate approximately twice that of N irradiation. This may be result of enhanced cellular progression triggered by cytoplasmic damage. These findings clearly demonstrate that not only DNA damage but also cytoplasmic damage contribute significantly to MN induction, suggesting a more complex interplay between cellular organelles during radiation exposure.journal articl
Superiority Illusion in Older Adults: Volume and Functional Connectivity of the Precuneus
No full textAim Positive thinking, which has been known to extend the lifespan, tends to increase with age. One specific form of positive thinking, the superiority illusion (SI), involves the belief that one is better than others. Despite its potential benefits in aging, the neural basis of the SI in elderly populations remains underexplored.
Methods This study combined a behavioral task, voxel-based morphometry (VBM), and resting-state functional connectivity (rsFC) analyses to investigate the neural substrates of the SI in a cohort of 100 participants, including young (N = 33), middle-aged (N = 33), and older adults (N = 34).
Results Our findings indicated that higher SI scores in older adults were correlated with greater gray matter volume in the right precuneus and stronger rsFC between the right precuneus and the left lateral occipital cortex. However, these correlations were not evident in younger and middle-aged groups.
Conclusions Our findings underscore the importance of the right precuneus and its connectivity in the manifestation of the SI, particularly in older adults, highlighting its potential role in adaptive aging processes.journal articl
SUPPRESOR OF GAMMA RESPONSE 1 promotes early onset of endoreplication upon DNA double-strand breaks by inducing CCS52A1 expression in Arabidopsis roots
No full textLiving organisms are constantly at the risk of DNA damage caused by factors such as DNA replication errors, reactive oxygen species, and UV radiation. In plants, DNA damage activates the NAC-type transcription factor SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1) that governs DNA damage responses such as cell cycle arrest, stem cell death, and early onset of endoreplication. However, molecular mechanisms underlying the early induction of endoreplication onset in response to DNA damage remain elusive. In this study, we show that CELL CYCLE SWITCH 52 A1 (CCS52A1), an activator of the APC/C E3 ligase, plays a major role in the early onset of endoreplication in response to DNA double-strand breaks (DSBs) in Arabidopsis roots. Upon DSBs, SOG1 directly binds to the CCS52A1 locus, thereby inducing its expression. Moreover, early transition to endoreplication in response to DSBs is suppressed in ccs52a1 knockout roots. Our data propose that increased polyploidy may function as a unique adaptative mechanism to genotoxic stress in plants.journal articl
Photon Vortex Generation from Nonlinear Compton Scattering in Feynman Approach
No full textIn this letter, we present calculation of nonlinear Compton scattering with high-energy electrons on circular polarized photons in a cylindrical coordinate using Feynman Approach, where an electron absorbs multi-photons and emit a photon. We take the plane wave function for the initial electrons and the incident photons. We also take the photon vortex wave function based on Bessel function for the emitted photon. A photon vortex is an eigenstate of the z-component of the total angular momentum (zTAM) when the photon goes on zaxis. The result shows that when N photons are absorbed the photon vortex with zTAM = N predominantly radiated. In this approach, it is possible to calculate nonlinear Compton scattering in various photon densities. This is useful for the study of astrophysical phenomena and prediction of experiments with intensity turntable laser.journal articl