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Pore fluid pressure on subduction zone megathrusts is lowered by fluid drainage into the overlying plate, affecting subduction zone seismicity. However, the spatial and temporal scales of fluid flow through suprasubduction zones are poorly understood. We constrain the duration and velocity of fluid flow through a shallow mantle wedge based on the analyses of vein networks consisting of high-temperature serpentine in hydrated ultramafic rocks from the Oman ophiolite. On the basis of a diffusion model and the time-integrated fluid flux, we show that the channelized fluid flow was short-lived (2.1 × 10 −1 to 1.1 × 10 1 years) and had a high fluid velocity (2.7 × 10 −3 to 4.9 × 10 −2 meters second −1 ), which is close to the propagation velocities of seismic events in present-day subduction zones. Our results suggest that the drainage of fluid into the overlying plate occurs as episodic pulses, which may influence the recurrence of megathrust earthquakes.

The dose of direct oral anticoagulants (DOACs) must be determined based on package insert recommendations. There are reports on the rate of inappropriate DOAC dose usage defined as a dose deviating from the approved dose in the package insert but no reports on factors that led to such deviations. Thus, patients who were admitted to the Suzuka Kaisei Hospital between 1 April 2016 and 31 March 2017 were chosen as subjects. Moreover, the factors that during hospitalization led to dose deviation from the package-insert DOAC dose were retrospectively examined. The characteristics of patients administered doses deviating from the package insert were compared with those of patients in the appropriate-dose group. The finding was that the proportion concomitantly administered antiplatelet agents was higher in the underdose group. In contrast, deviations from the recommended dose did not occur when DOACs were combined with CYP3A4 inhibitors or P-glycoprotein (P-gp) inhibitors. It was suggested that increase in the risk of hemorrhage by antiplatelet agents in combination with oral anticoagulants could explain deviations from the stipulated DOAC dose. In addition, a higher proportion of patients in the overdose group showed depressed Ccr, and gastrointestinal bleeding. In future, it will be necessary to propose principle-based dose changes for patients administered doses deviating from the package insert. If an underdose is administered, it is important to make a dose change that takes the concomitant drugs into consideration.

An azimuthal-rotation sample holder, with improvements in the rotation-angle accuracy and rotation-axes displacement during azimuthal rotation, was developed for molecular-orientation analysis using scanning transmission X-ray microscopy., In this study, an azimuthal-rotation sample holder compatible with scanning transmission X-ray microscopy was developed. This holder exhibits improvement in the accuracy of rotation angles and reduces the displacement of the rotation axes during azimuthal rotation by using a crossed roller bearing. To evaluate the performance of the holder, the authors investigated the dependence of the optical density around the C K-edge absorption of π-orbital-oriented domains in natural spherical graphite on the rotational angle by using linearly horizontally and vertically polarized undulator radiation. Based on the dependence of the optical density ratio between C 1s → π* and 1s → σ* excitation on the polarization angle of the X-rays, the average two-dimensional orientation angle of the π orbital in each position in a natural spherical graphite sample was visualized.

This paper proposes a data analysis method using persistent homology and nonnegative matrix factorization. A concatenated persistence image technique is used to extract coexisting structures from the persistence diagrams of different dimensions hidden behind the data. To demonstrate the potential of our method, we apply the method to 3D voxel data of iron ore sinters obtained by X-ray computed tomography. The analysis successfully captures the coexistence structures in these iron ore sinters.

A void formation at nanoscale and a crack initiation at micrometer scale in CFRP during a tensile test were investigated by means of positron annihilation and X-ray computed tomography (X-CT). Free volumes in bisphenol-A epoxy resin in CFRP were probed, and a mean diameter of free volumes at room temperature was determined to be 0.49 nm. The crack initiation and propagation in the CFRP sample was observed by in-situ measurements of X-CT during a tensile test. For the sample after the tensile test, free volumes with a mean diameter of 0.70 nm were introduced near fractures locations. In the same locations, the density of free volumes which intrinsically existed in the polymer resins decreased. Thus, the introduction of the free volumes was attributed to breaks in molecular chains upon fracture and a resultant agglomeration of intrinsic free volumes in the polymer matrix.

The mechanical properties of carbon fibers (CFs) can be controlled by their internal structures such as the distribution of &pi, orbital-oriented domains, as well as the diameter and cross-sectional shape of the fiber. In this study, we investigated the carbon chemical structure maps of commercial polyacrylonitrile (PAN)- and pitch-based CFs using scanning transmission X-ray microscopy to evaluate the differences in the distribution of &pi, orbital-oriented domains. The graphene sheets in the PAN-based CFs have a fiber texture that is aligned along the fiber direction and randomly oriented within the cross section. The domain sizes within the cross section are less than the resolution limit (i.e., 50 nm). By contrast, the graphene sheets in the pitch-based CFs are aligned parallel to each other and form aggregates with a size ranging from approximately 100 nm to 1 &mu, m within the cross sections. They form 200&ndash, 300-nm stripes along the CF axis in the longitudinal sections.

The present situation of the XAFS database in Japan and a proposal for the construction of an international collaboration XAFS database are presented., The present state of XAFS databases, particularly in Japan, and proposals for future directions are presented. International collaboration is important for enlarging the database for further development of XAFS spectroscopy.

Tortuosity, permeability, and pore radius, which are parameters in the Biot model, are important for analyzing the elastic wave propagation in water-saturated unconsolidated marine sands. In this study, the formation factor and permeability are measured for 34 kinds of water-saturated glass beads and sands with uniformly sized grains and 73 kinds of water-saturated sands with distributed sized grains. Using these measured data, the empirical equations for the formation factor, cementation exponent, and tortuosity are obtained. The pore shape factor, k 0, in the Kozeny–Carman model and pore shape factor, a, in the Revil–Cathles (RC) model are derived. The Hazen, Kozeny–Carman, and RC models are compared for the measured permeability results. Furthermore, the relationship between the tortuosity and permeability is shown. Finally, the ratio of the effective pore radius to effective mean grain diameter is derived.Tortuosity, permeability, and pore radius, which are parameters in the Biot model, are important for analyzing the elastic wave propagation in water-saturated unconsolidated marine sands. In this study, the formation factor and permeability are measured for 34 kinds of water-saturated glass beads and sands with uniformly sized grains and 73 kinds of water-saturated sands with distributed sized grains. Using these measured data, the empirical equations for the formation factor, cementation exponent, and tortuosity are obtained. The pore shape factor, k 0, in the Kozeny–Carman model and pore shape factor, a, in the Revil–Cathles (RC) model are derived. The Hazen, Kozeny–Carman, and RC models are compared for the measured permeability results. Furthermore, the relationship between the tortuosity and permeability is shown. Finally, the ratio of the effective pore radius to effective mean grain diameter is derived.

Macroscopic phenomena, such as fracture, corrosion, and degradation of materials, are associated with various reactions which progress heterogeneously. Thus, material properties are generally determined not by their averaged characteristics but by specific features in heterogeneity (or ‘trigger sites’) of phases, chemical states, etc., where the key reactions that dictate macroscopic properties initiate and propagate. Therefore, the identification of trigger sites is crucial for controlling macroscopic properties. However, this is a challenging task. Previous studies have attempted to identify trigger sites based on the knowledge of materials science derived from experimental data (‘empirical approach’). However, this approach becomes impractical when little is known about the reaction or when large multi-dimensional datasets, such as those with multiscale heterogeneities in time and/or space, are considered. Here, we introduce a new persistent homology approach for identifying trigger sites and apply it to the heterogeneous reduction of iron ore sinters. Four types of trigger sites, ‘hourglass’-shaped calcium ferrites and ‘island’- shaped iron oxides, were determined to initiate crack formation using only mapping data depicting the heterogeneities of phases and cracks without prior mechanistic information. The identification of these trigger sites can provide a design rule for reducing mechanical degradation during reduction.

Voids and cracks can fatally degrade structural materials such as metals and ceramics but are tolerated in carbon fibre-reinforced plastic (CFRP) composites if monitored to prevent their growth to a critical size. Thus, the use of CFRPs as aeronautical structural materials requires an understanding of microscopic crack formation. However, this crack-formation mechanism remains unclear because experimental difficulties have hindered studies of relevant phenomena that occur before crack formation. Herein, we report high-resolution (~50 nm) and non-destructive three-dimensional observations of crack initiation and propagation under applied stress. This evaluation reveals that voids and cracks do not simply result from local stresses but instead occur largely through two competing nanoscale mechanisms, namely, fibre/plastic interface debonding and in-plastic crack initiation. Therefore, nanoscopic insights into these heterogeneities are essential for controlling crack initiation and determining reasonable safety margins for CFRP composite use.

Plastic deformation of polycrystalline materials under shock wave loading is a critical characteristic in material science and engineering. However, owing to the nanosecond time scale of the shock-induced deformation process, we currently have a poor mechanistic understanding of the structural changes from atomic scale to mesoscale. Here, we observed the dynamic grain refinement of polycrystalline aluminum foil under laser-driven shock wave loading using time-resolved X-ray diffraction. Diffraction spots on the Debye-Scherrer ring from micrometer-sized aluminum grains appeared and disappeared irregularly, and were shifted and broadened as a result of laser-induced shock wave loading. Behind the front of shock wave, large grains in aluminum foil were deformed, and subsequently exhibited grain rotation and a reduction in size. The width distribution of the diffraction spots broadened because of shock-induced grain refinement and microstrain in each grain. We performed quantitative analysis of the inhomogeneous lattice strain and grain size in the shocked polycrysalline aluminum using the Williamson-Hall method and determined the dislocation density under shock wave loading.

The crack initiation and propagation under the application of opening load were analyzed in situ using nondestructive synchrotron radiation X-ray computed tomography (nanoscopic SR X-CT) with a spatial resolution of ∼50 nm. The results show that the voids and cracks initiation are not only the result of local stresses but also are due to two competing nanoscale mechanisms, that is, fiber/plastic interface debonding and in-resin crack initiation. In the “thin” epoxy region in which the resin thickness between the adjacent carbon fibers is small, cracks propagate mainly by debonding along the carbon fiber/epoxy interface. In the “thick” epoxy region in which the resin thickness between the carbon fibers is large, cracks propagate through the extensive plastic deformation of the epoxy resin, and the propagation mechanism largely depends on the resin thickness, which affects the plastic deformation behavior of the epoxy around the crack tip. Voids (sub-μm) often form in front of the crack tip and merge with the propagating cracks. Nanoscopic SR X-CT provides indispensable information on these nanoscale mechanisms, which cannot be obtained with traditional methods, including macroscopic observations and mechanical theory. These nanoscale mechanisms are essential for the mechanical modeling and analysis at multi-scales.

The Materials Chemistry Group of the Institute of Materials Structure Science, KEK, aims to clarify irreversible reaction processes such as structural changes of materials induced by laser shock or temperature. We have developed an experimental system using dispersive X-ray absorption fine structure (DXAFS) spectroscopy and a laser to observe these processes in real time. Destruction or a phase transition is triggered by a laser synchronized with an X-ray pulse. Previous experiments have deployed a simple sample exchanger that could load about 50 samples. For more efficient experiments, we developed a new sample exchange robot that can load about 3,000 samples and a large chamber for an oxygen-free atmosphere. The robot, the laser system, and an infrared thermometer were implemented in the chamber. The developed experimental system was installed at PF-AR-NW2A beamline in November 2017. Since then we have confirmed the effectiveness of the new robot in DXAFS experiments.

We have developed a type of surface sensitive x-ray spectroscopy, which is called total reflection x-ray spectroscopy (TREXS). As x-ray absorption fine structure (XAFS) spectroscopy is used to study many materials, TREXS provides structural and electronic information with the surface sensitivity of ~2–3 nm, and will be a powerful method to study surfaces. It is required, however, to observe surface chemical species to understand surface chemical reactions more comprehensively. Infrared reflection absorption spectroscopy (IRRAS) is suitable to detect surface chemical species, and the multi-modal surface research equipment of TREXS combined with IRRAS has been developed. The performance of the developed equipment was confirmed by measuring TREXS and IRRAS spectra for the NiO/Ni(30 nm)/Si and Ni(30 nm)/Si samples. The equipment can be applied to study various surface chemical reactions under gaseous conditions.

We have developed hard X-ray spectromicroscopes at various scales using synchrotron radiation to elucidate the origin of the function of materials at Photon Factory (PF), Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK) in Japan. One is a 2D scanning X-ray microscope with ∼20-µm spatial resolution at BL-15A1 in PF; another is full-field 3D X-ray computed tomography (X-CT) with a resolution down to 30 nm at NW2A in PF-AR. In both techniques, not only morphological images but also X-ray absorption spectra (XAS) at any pixel or voxel of interest can be obtained by changing the X-ray energy. These XAS imaging techniques are useful for understanding the chemical states of specific elements and investigating reaction mechanisms. We have applied these techniques to various materials and elucidated the change of heterogeneity in chemical states which determines macroscopic properties. Application to heterogeneous reduction in iron ore sinters demonstrated clearly the impact of this approach; the multi-scale heterogeneity from 50 nm to 20 µm was shown to be related to trigger sites, which determine the degradation of iron ore sinters during reduction.

Journal of synchrotron radiation 25(4), 935 - 943 (2018). doi:10.1107/S1600577518003752, Round robin studies have been used across fields of science for quality control testing and to investigate laboratory dependencies and cross-platform inconsistencies as well as to drive forward the improvement of understanding of experimental systems, systematic effects and theoretical limitations. Here, following the Q2XAFS Workshop and Satellite to IUCr Congress 2017 on `Data Acquisition, Treatment, Storage – quality assurance in XAFS spectroscopy', a mechanism is suggested for a suitable study across XAFS (X-ray absorption fine-structure) beamlines and facilities, to enable each beamline to cross-calibrate, provide representative test data, and to enable collaborative cross-facility activities to be more productive., Published by Wiley-Blackwell, [S.l.]

The reported compressional wave speed dispersion and attenuation could be explained by a modified gap stiffness model incorporated into the Biot model (the BIMGS model). In contrast, shear wave speed dispersion and attenuation have not been investigated in detail. No measurements of shear wave speed dispersion have been reported, and only Brunson's data provide the frequency characteristics of shear wave attenuation. In this study, Brunson's attenuation measurements are compared to predictions using the Biot-Stoll model and the BIMGS model. It is shown that the BIMGS model accurately predicts the frequency dependence of shear wave attenuation. Then, the shear wave speed dispersion and attenuation in water-saturated silica sand are measured in the frequency range of 4-20 kHz. The vertical stress applied to the sample is 17.6 kPa. The temperature of the sample is set to be 5 °C, 20 °C, and 35 °C in order to change the relaxation frequency in the BIMGS model. The measured results are compared with those calculated using the Biot-Stoll model and the BIMGS model. It is shown that the shear wave speed dispersion and attenuation are predicted accurately by using the BIMGS model.

We have succeeded in in situ and simultaneously observing the redox reaction of palladium and the oxygen storage/release process in a newly developed palladium-promoted Sr­Fe­O (Pd/Sr­Fe­O) catalyst during redox-gas cycles using dispersive X-ray absorption fine structure (XAFS) analysis at 673K with a time resolution of less than 20ms. The Pd/Sr­Fe­O catalyst, which exhibits high performance for automotive emission control, has a unique “multi-phase-domain” structure, where a single grain is composed of nano-sized domains of three phases: SrFeO3¹¤ ,S r4Fe6O13¹¤ and SrFe12O19¹¤. In situ observation has shown a strong correlation between the redox of the palladium and the oxygen storage/release in the Pd/Sr­Fe­O catalyst, and the correlation factors differ between the reduction and oxidation reactions. The oxide phases exhibit a type of “oxygen buffer” effect in the oxidation cycle and delay the formation of Pd­O, resulting in the high performance of the catalyst.

The large velocity dispersion recently reported could be explained by a gap stiffness model incorporated into the Biot model (the BIMGS model) proposed by the author. However, at high frequencies, some measured results have been reported for negative velocity dispersion and attenuation proportional to the first to fourth power of frequency. In this study, first, it is shown that the results of velocity dispersion and attenuation calculated using the BIMGS model are consistent with the results measured in two kinds of water-saturated sands with different grain sizes, except in the high-frequency range. Then, the velocity dispersion and attenuation in six kinds of water-saturated glass beads and four kinds of water-saturated silica sands with different grain sizes are measured in the frequency ranges of 80-140 and 300-700 kHz. The measured results are compared with those calculated using the BIMGS model plus some acoustic models. It is shown that the velocity dispersion and attenuation are well predicted by using the BIMGS model in the range of kd ≤ 0.5 (k: wavenumber in water, d: grain diameter) and by using the BIMGS model plus multiple scattering effects in the range of kd ≥ 0.5 in which negative velocity dispersion appears.