ORCID Profile
0000-0003-2579-513X
Current Organisation
Japan Synchrotron Radiation Research Institute
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Publisher: Public Library of Science (PLoS)
Date: 04-2014
Publisher: Elsevier BV
Date: 11-2013
Publisher: International Union of Crystallography (IUCr)
Date: 2020
DOI: 10.1107/S1600577519014863
Abstract: Small-animal physiology studies are typically complicated, but the level of complexity is greatly increased when performing live-animal X-ray imaging studies at synchrotron and compact light sources. This group has extensive experience in these types of studies at the SPring-8 and Australian synchrotrons, as well as the Munich Compact Light Source. These experimental settings produce unique challenges. Experiments are always performed in an isolated radiation enclosure not specifically designed for live-animal imaging. This requires equipment adapted to physiological monitoring and test-substance delivery, as well as shuttering to reduce the radiation dose. Experiment designs must also take into account the fixed location, size and orientation of the X-ray beam. This article describes the techniques developed to overcome the challenges involved in respiratory X-ray imaging of live animals at synchrotrons, now enabling increasingly sophisticated imaging protocols.
Publisher: Research Square Platform LLC
Date: 16-03-2023
DOI: 10.21203/RS.3.RS-2389559/V1
Abstract: Volatile components are abundant in carbonaceous asteroids and can be important tracers for the evolution of asteroid surfaces interacting with the space environment, but their behavior on airless surfaces is poorly understood. S les from the C-type carbonaceous asteroid Ryugu show dehydration of phyllosilicate, indicating ongoing surface modifications on the aqueously-altered asteroid. Here we report the analysis of Ryugu s les showing selective liberation of carbon, oxygen, and sulfur from iron-rich oxide, sulfide, and carbonate, which are major products of aqueous alteration. These mineral surfaces are decomposed to metallic iron, iron nitride, and magnesium-iron oxide. The modifications are most likely caused by solar wind implantation and micrometeorite impacts and are distinct indicators of surface space exposure over 10 3 years. Nitridation of metallic iron may require micrometeorites rich in solid nitrogen compounds, which implies that the amount of nitrogen available for planetary formation in the inner solar system is larger than previously recognized.
Publisher: IOP Publishing
Date: 12-01-2012
Publisher: Public Library of Science (PLoS)
Date: 30-01-2013
Publisher: Elsevier BV
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 07-08-1900
DOI: 10.1038/S41550-022-01841-6
Abstract: Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of s les from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe 3+ to Fe 2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.
Publisher: Springer Science and Business Media LLC
Date: 30-07-2018
DOI: 10.1038/S41598-018-29841-5
Abstract: Phase contrast X-ray imaging (PCXI) is an emerging imaging modality that has the potential to greatly improve radiography for medical imaging and materials analysis. PCXI makes it possible to visualise soft-tissue structures that are otherwise unresolved with conventional CT by rendering phase gradients in the X-ray wavefield visible. This can improve the contrast resolution of soft tissues structures, like the lungs and brain, by orders of magnitude. Phase retrieval suppresses noise, revealing weakly-attenuating soft tissue structures, however it does not remove the artefacts from the highly attenuating bone of the skull and from imperfections in the imaging system that can obscure those structures. The primary causes of these artefacts are investigated and a simple method to visualise the features they obstruct is proposed, which can easily be implemented for preclinical animal studies. We show that phase contrast X-ray CT (PCXI-CT) can resolve the soft tissues of the brain in situ without a need for contrast agents at a dose ~400 times lower than would be required by standard absorption contrast CT. We generalise a well-known phase retrieval algorithm for multiple-material s les specifically for CT, validate its use for brain CT, and demonstrate its high stability in the presence of noise.
Publisher: Springer Science and Business Media LLC
Date: 14-08-2014
Publisher: Springer Science and Business Media LLC
Date: 28-09-2013
Publisher: Springer Science and Business Media LLC
Date: 21-11-2017
DOI: 10.1038/S41598-017-16264-X
Abstract: Phase-contrast X-ray imaging can improve the visibility of weakly absorbing objects (e.g. soft tissues) by an order of magnitude or more compared to conventional radiographs. Combining phase retrieval with computed tomography (CT) can increase the signal-to-noise ratio (SNR) by up to two orders of magnitude over conventional CT at the same radiation dose, without loss of image quality. Our experiments reveal that as the radiation dose decreases, the relative improvement in SNR increases. We show that this enhancement can be traded for a reduction in dose greater than the square of the gain in SNR. Upon reducing the dose 300 fold, the phase-retrieved SNR was still up to 9.6 ± 0.2 times larger than the absorption contrast data with spatial resolution in the tens of microns. We show that this theoretically reveals the potential for dose reduction factors in the tens of thousands without loss in image quality, which would have a profound impact on medical and industrial imaging applications.
Publisher: International Union of Crystallography (IUCr)
Date: 2021
DOI: 10.1107/S1600577520013995
Abstract: Analyser-based phase-contrast imaging (ABPCI) is a highly sensitive phase-contrast imaging method that produces high-contrast images of weakly absorbing materials. However, it is only sensitive to phase gradient components lying in the diffraction plane of the analyser crystal [ i.e. in one dimension (1-D)]. In order to accurately account for and measure phase effects produced by the wavefield-s le interaction, ABPCI and other 1-D phase-sensitive methods must achieve 2-D phase gradient sensitivity. An inclined geometry method was applied to a Laue geometry setup for X-ray ABPCI through rotation of the detector and object about the optical axis. This allowed this traditionally 1-D phase-sensitive phase-contrast method to possess 2-D phase gradient sensitivity. Tomographic datasets were acquired over 360° of a multi-material phantom with the detector and s le tilted by 8°. The real and imaginary parts of the refractive index were reconstructed for the phantom.
Publisher: Springer Science and Business Media LLC
Date: 20-12-2021
DOI: 10.1038/S41550-021-01550-6
Abstract: C-type asteroids 1 are considered to be primitive small Solar System bodies enriched in water and organics, providing clues to the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing 2–7 and on-asteroid measurements 8,9 with Hayabusa2 (ref. 10 ). However, the ground truth provided by laboratory analysis of returned s les is invaluable to determine the fine properties of asteroids and other planetary bodies. We report preliminary results of analyses on returned s les from Ryugu of the particle size distribution, density and porosity, spectral properties and textural properties, and the results of a search for Ca–Al-rich inclusions (CAIs) and chondrules. The bulk s le mainly consists of rugged and smooth particles of millimetre to submillimetre size, confirming that the physical and chemical properties were not altered during the return from the asteroid. The power index of its size distribution is shallower than that of the surface boulder observed on Ryugu 11 , indicating differences in the returned Ryugu s les. The average of the estimated bulk densities of Ryugu s le particles is 1,282 ± 231 kg m −3 , which is lower than that of meteorites 12 , suggesting a high microporosity down to the millimetre scale, extending centimetre-scale estimates from thermal measurements 5,9 . The extremely dark optical to near-infrared reflectance and spectral profile with weak absorptions at 2.7 and 3.4 μm imply a carbonaceous composition with indigenous aqueous alteration, matching the global average of Ryugu 3,4 and confirming that the s le is representative of the asteroid. Together with the absence of submillimetre CAIs and chondrules, these features indicate that Ryugu is most similar to CI chondrites but has lower albedo, higher porosity and more fragile characteristics.
Publisher: Springer Science and Business Media LLC
Date: 26-12-2013
DOI: 10.1038/PR.2012.197
Abstract: Recent phase-contrast X-ray imaging studies suggest that inspiration primarily drives lung aeration and airway liquid clearance at birth, which questions the role of adrenaline-induced activation of epithelial sodium channels (ENaCs). We hypothesized that pressures generated by inspiration have a greater role in airway liquid clearance than do ENaCs after birth. Rabbit pups (30 d of gestation) were delivered and sedated, and 0.1 ml of saline (S) or amiloride (Am an ENaC inhibitor) was instilled into the lungs before mechanical ventilation. Two other groups (30 d of gestation) were treated similarly but were also given adrenaline (S/Ad and Am/Ad) before mechanical ventilation. Amiloride and adrenaline did not affect functional residual capacity (FRC) recruitment (P > 0.05). Amiloride increased the rate of FRC loss between inflations (Am: -5.2 ± 0.6 ml/kg/s), whereas adrenaline reduced the rate of FRC loss (S/Ad: -1.9 ± 0.3 ml/kg/s) as compared with saline-treated controls (S: -3.5 ± -0.6 ml/kg/s P < 0.05). These data indicate that inspiration is a major determinant of airway liquid clearance and FRC development during positive pressure ventilation. Although ENaC inhibition and adrenaline administration had no detectable effect on FRC development, ENaC may help to prevent liquid from re-entering the airways during expiration.
Publisher: International Union of Crystallography (IUCr)
Date: 2016
DOI: 10.1107/S1600577515021700
Abstract: This work utilized synchrotron imaging to achieve a regional assessment of the lung's response to imparted oscillations. The forced oscillation technique is increasingly being used in clinical and research settings for the measurement of lung function. During the forced oscillation technique, pressure oscillations are imparted to the lungs via the subjects' airway opening and the response is measured. This provides information about the mechanical properties of the airways and lung tissue. The quality of measurements is dependent upon the input signal penetrating uniformly throughout the lung. However, the penetration of these signals is not well understood. The development and use of a novel image-processing technique in conjunction with synchrotron-based imaging was able to regionally assess the lungs' response to input pressure oscillation signals in anaesthetized mice. The imaging-based technique was able to quantify both the power and distribution of lung tissue oscillations during forced oscillations of the lungs. It was observed that under forced oscillations the apices had limited lung tissue expansion relative to the base. This technique could be used to optimize input signals used for the forced oscillation technique or potentially as a diagnostic tool itself.
Publisher: Springer Science and Business Media LLC
Date: 18-03-2016
DOI: 10.1038/PR.2016.59
Publisher: Trans Tech Publications, Ltd.
Date: 12-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.626.200
Abstract: This paper demonstrates how recent progress for real-time solidification observation at SPring-8 synchrotron has contributed to the development of Sn-7wt%Cu-0.05wt%Ni high temperature lead-free solder alloys. Lead-free solder alloys in the composition range Sn-0.7 to 7.6wt%Cu that consist of primary Cu 6 Sn 5 in a eutectic Sn-Cu 6 Sn 5 matrix have been proposed as solders for application at temperatures up to 400°C for the assembly high current semiconductors. It is shown that trace levels of Al have a marked effect on the solder microstructure and refine the size of the primary Cu 6 Sn 5 . The solidification pathway that leads to the refinement was observed in real-time using X-ray synchrotron observations.
Publisher: AIP
Date: 2012
DOI: 10.1063/1.4742280
Publisher: IOP Publishing
Date: 11-06-2015
Publisher: Trans Tech Publications, Ltd.
Date: 10-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/SSP.192-193.185
Abstract: Synchrotron radiography experiments are overviewed that directly image semi-solid deformation at the globule-scale. Globular Al-15Cu at 50-60% solid was deformed in direct-shear at 10-2 s-1. Deformation is shown to occur by globule rearrangement without discernible deformation of the in idual globules. Globules were found to translate and rotate as quasi-discrete bodies in response to forces acting at globule-globule contacts, similar to liquid-saturated granular materials such as water-saturated sand. Rearrangement caused the globule packing-density (the solid fraction) to adjust by local compaction and local dilation of the globule assembly, and deformation is highly inhomogeneous. During shear, there was a net dilation and strain began to localize into a shear band of decreased solid fraction by the end of the experiments.
No related grants have been discovered for Kentaro Uesugi.