Morphological and compositional features of corrosion behavior of SUS410–SUS410, SUS316–SUS316 and SUS410–SUS316 TIG welded joints in Li

The corrosion behavior of SUS410–SUS410, SUS316–SUS316, SUS410–SUS316 tungsten inert gas welded joints in static Li at 600 °C for 250 h was investigated as applied for lithium-cooled systems of fusion reactor. The different regions of welded joints (base metal, weld metal, heat affected zone, fusion layer) possessed by the same phase state (ferrite or austenite) showed no substantial difference in the corrosion behavior under the given conditions of test. The corrosion attack resulted in the marked depletion of corresponded near-surface layers with chromium and nickel. The clear corrosion induced refining of surface grain structure, in comparison with initial surface morphology (polished) and corresponded bulk grain size, was observed indicating about the prevalence of the grain boundary corrosion attack during which the low-angle sub-boundaries transform into the large-angle due to the increase in their defectiveness.     

Structural Insights into the Molecular Design of Flutolanil Derivatives Targeted for Fumarate Respiration of Parasite Mitochondria

Recent studies on the respiratory chain of Ascaris suum showed that the mitochondrial NADH-fumarate reductase system composed of complex I, rhodoquinone and complex II plays an important role in the anaerobic energy metabolism of adult A. suum. The system is the major pathway of energy metabolism for adaptation to a hypoxic environment not only in parasitic organisms, but also in some types of human cancer cells. Thus, enzymes of the pathway are potential targets for chemotherapy. We found that flutolanil is an excellent inhibitor for A. suum complex II (IC₅₀ = 0.058 μM) but less effectively inhibits homologous porcine complex II (IC₅₀ = 45.9 μM). In order to account for the specificity of flutolanil to A. suum complex II from the standpoint of structural biology, we determined the crystal structures of A. suum and porcine complex IIs binding flutolanil and its derivative compounds. The structures clearly demonstrated key interactions responsible for its high specificity to A. suum complex II and enabled us to find analogue compounds, which surpass flutolanil in both potency and specificity to A. suum complex II. Structures of complex IIs binding these compounds will be helpful to accelerate structure-based drug design targeted for complex IIs.     

Structural and compositional transformations in the near-surface layers of Fe–Cr based steels exposed to lithium – Effect of alloying and corrosion-assisted substructure coarsening

The corrosion behaviour of RAF/M RUSFER-EK-181 and F/M (EP-823, SUS410) steels was investigated in static “pure” (0.004 wt.% N) and N-added Li (0.5 wt.% N) at 600 °C up to 750 h. The weight losses of samples increased with time and nitrogen content in Li. The corrosion-assisted coarsening was observed in the near-surface layers of RAF/M steels. It is caused by the dissolution of Cr and decomposition of carbides during exposure to both melts. The coarsening mechanism and the influence of alloying on the structural and compositional transformations in steels exposed to Li are discussed.     

Analysis of Lignin Aromatic Structure in Wood Fractions Based on IR Spectroscopy

In our previous studies, a method of quantitative analysis of lignin structure by IR spectroscopy with direct use of wood meal was developed which can be apply to a wide range of wood species. Lignin structure deposition in different fractions in the same wood sample also has characteristic diversity and differences. In this study, quantitative analysis of lignin structure by IR spectroscopy was used to determine whether it can be applied to different fractions in the same wood sample. Finely milled beech wood was fractionated by stepwise extraction using aqueous dioxane and followed by subsequent dimethyl sulfoxide (DMSO)/LiCl solvents with increasing LiCl concentrations. The results showed that fractions of the peak area ratio of log(1595/1509) fit a linear relationship with different wood species very well. Therefore, log(1595/1509) could be used not only with different wood species but also with different fractions from the same wood. For 1509/1460, log(1275/1220), 1130/1030 and 835/(835+815), different fractions deviated from the original relationship obtained from different wood species.     

Topological phenomena in quantum walks: elementary introduction to the physics of topological phases

Discrete quantum walks are dynamical protocols for controlling a single quantum particle. Despite of its simplicity, quantum walks display rich topological phenomena and provide one of the simplest systems to study and understand topological phases. In this article, we review the physics of discrete quantum walks in one and two dimensions in light of topological phenomena and provide elementary explanations of topological phases and their physical consequence, namely the existence of boundary states. We demonstrate that quantum walks are versatile systems that simulate many topological phases whose classifications are known for static Hamiltonians. Furthermore, topological phenomena appearing in quantum walks go beyond what has been known in static systems; there are phenomena unique to quantum walks, being an example of periodically driven systems, that do not exist in static systems. Thus the quantum walks not only provide a powerful tool as a quantum simulator for static topological phases but also give unique opportunity to study topological phenomena in driven systems.     

Current Sensitivity Enhancement of a Quasi-One-Junction SQUID Comparator as an Input Circuit of SFQ Readout Circuit for a Superconducting Detector

We evaluated the current sensitivity of a quasi-one-junction SQUID (QOS) comparator with an input transformer at 4.2 K. A comparator based on a QOS is promising for constructing the single flux quantum (SFQ) readout circuits of an array system of multiple superconducting detectors.The QOS comparator is made of three Nb/AlO \(_x\) /Nb Josephson junctions, senses an output signal of a superconductor detector, and generates the SFQ pulses.There are strong demands for enhancing the current sensitivity of the QOS comparator because an output current from superconducting detector typically remains at the magnitude of a few \(\upmu \) A. We fabricated the QOS comparator with an input transformer using AIST Standard Process 2, where the critical current density of the Josephson junctions is chosen as high as 2.5 kA/cm \(^{2}\) . We designed the input transformer to enhance the current sensitivity under the conditions of 200  \(\upmu \) m  \(\times \)  200  \(\upmu \) m in size and 20:1 in turn ratio. Consequently, we succeeded in reducing a gray zone width of the comparator, and achieved the current sensitivity of 400 nA at 4.2 K in the low frequency range.     

Origin of Surface Coating Effect for MgO on LiCoO2 to Improve the Interfacial Reaction between Electrode and Electrolyte

Surface coating on lithium‐ion battery cathodes improves their durability at high potentials, which is a well‐known practical application. However, the mechanism is still unclear because the coating influences the electrode/electrolyte interface at a few nanometer‐scale and direct observation of the interface under real operating conditions of a battery is challenging. This study reveals the mechanism of the surface coating effect on lithium‐ion battery cathodes by using in operando X‐ray absorption spectroscopy (XAS) on well‐defined MgO‐coated LiCoO₂ thin‐film electrodes prepared via pulsed laser deposition. Total‐reflection in operando XAS measurements reveal that LiCoO₂ forms a reductive phase at the interface between the uncoated‐LiCoO₂ electrode and the electrolyte, while the MgO coating layer inhibits the redox process, leading to an improvement in the cycle performance of the battery. Depth‐resolved in operando XAS measurements indicate that a solid solution of the magnesium phase forms at the LiCoO₂ surface upon MgO coating. Magnesium ions function as pillars to stabilize the layered structure at the interface between the LiCoO₂ electrode and the electrolyte for delithiated states upon cycling at potentials.     

Impacts of surface sulfurization on Cu(In1−x,Gax)Se2 thin‐film solar cells

In this work, the impacts of surface sulfurization of high‐quality Cu(In_1−x,Ga_x)Se₂ (CIGS) thin films deposited by three‐stage process on the film properties and the cell performance were investigated. The CIGS thin films were sulfurized at 550 °C for 30 min using H₂S gas. The X‐ray photoelectron spectroscopy analysis revealed that sulfur atoms diffused into the CIGS surface layer and that the valence band minimum was lowered by the film sulfurization. The open circuit voltage (V_oc) drastically increased from 0.590 to 0.674 V as a result of the sulfurization process. Temperature‐dependent current–voltage and capacitance–frequency measurements also revealed that interface recombination was drastically decreased by the lowering of the defect's activation energy level at the vicinity of the buffer/CIGS interface after the sulfurization. Copyright © 2014 John Wiley & Sons, Ltd.     

Cooperative 3D tunnel measurement based on 2D–3D registration of omnidirectional laser light

In this study, we proposed a high-density three-dimensional (3D) tunnel measurement method, which estimates the pose changes of cameras based on a point set registration algorithm regarding 2D and 3D point clouds. To detect small deformations and defects, high-density 3D measurements are necessary for tunnel construction sites. The line-structured light method uses an omnidirectional laser to measure a high-density cross-section point cloud from camera images. To estimate the pose changes of cameras in tunnels, which have few textures and distinctive shapes, cooperative robots are useful because they estimate the pose by aggregating relative poses from the other robots. However, previous studies mounted several sensors for both the 3D measurement and pose estimation, increasing the size of the measurement system. Furthermore, the lack of 3D features makes it difficult to match point clouds obtained from different robots. The proposed measurement system consists of a cross-section measurement unit and a pose estimation unit; one camera was mounted for each unit. To estimate the relative poses of the two cameras, we designed a 2D–3D registration algorithm for the omnidirectional laser light, and implemented hand-truck and unmanned aerial vehicle systems. In the measurement of a tunnel with a width of 8.8 m and a height of 6.4 m, the error of the point cloud measured by the proposed method was 162.8 and 575.3 mm along 27 m, respectively. In a hallway measurement, the proposed method generated less errors in straight line shapes with few distinctive shapes compared with that of the 3D point set registration algorithm with Light Detection and Ranging.     

Capacitive touchscreen‐integrated electrostatic tactile display with localized sensation

An electrostatic tactile display with a projected capacitive touchscreen integrated into a single panel was demonstrated. Every electrode on the panel is driven for both tactile presentation and the touch sensor. The functions are both time and spatially multiplexed, and a reference–node‐driven high‐pass filter in the touch controller filters out the noise from the tactile driving signals.