Effect of strain on “hardening by annealing and softening by deformation” phenomena in ultra-fine grained aluminum

Ultra-fine grained (UFG) metals fabricated by severe plastic deformation (SPD) sometimes exhibit peculiar mechanical properties. For example, the “hardening by annealing and softening by deformation” was reported in UFG aluminum, which was totally opposite to the behaviors of conventionally coarse-grained materials. In this study, the effect of SPD strain on the peculiar phenomena was investigated. The UFG aluminum was fabricated by various cycles of the accumulative roll-bonding (ARB) process with lubrication at ambient temperature. The specimen ARB-processed by ten cycles certainly showed the peculiar phenomena. On the other hand, the 6-cycle specimen did not show the phenomena but was softened by annealing and hardened by deformation normally. From the results of microstructural characterization, it was suggested that the difference in the change of the mechanical property during annealing and deformation between 6-cycle and 10-cycle specimens was caused by the difference in the grain size and/or the texture components, which depended on the SPD strain.     

A Novel α-Al2O3 Diesel Particulate Filter with Alkali Metal-Based Catalyst for Diesel Soot Oxidation

A diesel particulate filter (DPF) substrate was fabricated from alkali-resistant α-Al₂O₃ to make a practical use of alkali metal catalysts for diesel soot oxidation. The fundamental properties of the α-Al₂O₃-DPF, including its particle filtration efficiency, pressure drop, and thermal durability were comparable to those of the conventional DPFs. The diesel soot oxidation activity of the catalyzed α-Al₂O₃-DPF with a washcoat of alkali metal-based catalyst was, even after thermal aging, much higher than that of the conventional catalyzed-DPF with platinum group metal catalysts.     

Low dose exposure diagnosis with a transXend detector aiming for iodine-marked cancer detection

The energy resolved computed tomography (CT), which had advantage over conventional CT (twofold higher CT value for iodine contrast agent and being free from beam hardening effect), was shown practical by employing the transXend detector: it measured X-rays as electric current and gave energy distribution of incident X-rays after analysis. This article shows a new application of the transXend detector for estimating the thicknesses of acrylic, iodine, and aluminum in a phantom. For this purpose, the responses of the segment detectors in the transXend detector are changed intentionally with inserting filters. With previously obtained two-dimensional maps for acrylic–iodine and acrylic–aluminum thicknesses, which are shown by the ratios of electric currents measured by the segment detectors, the thickness of materials on the path of the X-rays are obtained by a transmission measurement.     

Tribo-Film Formation of Lubricant Additives on Cr-Plated Surface Sliding Against Nitrile–Butadiene Rubber

A Bowden and Leben type sliding tester was used with a base oil to evaluate four types of friction modifier additives—acid phosphate, hydrogen phosphite, acid phosphate amine salt, and amine—as a fundamental study on hydraulic fluid additives for sliding of nitrile–butadiene rubber on Cr-plated metal. Acid phosphate showed the lowest friction coefficient among the phosphorus acids. After the sliding test, the formation of tribo-films on the Cr-plated surface was investigated by Fourier transform infrared reflection absorption spectroscopy and a time-of-flight secondary ion mass spectrometer. The analytical results suggest that tribo-films formed by the phosphorus acids effectively reduced friction.     

Intrabody three-dimensional position sensor for an ultrasound endoscope

To avoid or reduce the X-ray exposure in endoscopic examinations and therapy, as an alternative to the conventional two-dimensional X-ray fluoroscopy we are developing an intrabody navigation system that can directly measure and visualize the three-dimensional (3-D) position of the tip and the trace of an ultrasound endoscope. The proposed system can identify the 3-D location and direction of the endoscope probe inserted into the body to furnish endoscopic images. A marker transducer(s) placed on the surface of the body transmits ultrasound pulses, which are visualized as a marker synchronized to the scanning of the endoscope. The position (direction and distance of the marker transducer(s) outside the body relative to the scanning probe inside the body) of the marker is detected and measured in the scanned image of the ultrasound endoscope. Further, an optical localizer locates the marker transducer(s) with six degrees of freedom. Thus, the proposed method performs inside-body 3-D localization by utilizing the inherent image reconstruction function of the ultrasound endoscope, and is able to be used with currently available commercial ultrasound image scanners. The system may be envisaged as a kind of global positioning system for intrabody navigation.     

Tunneling measurements of the superconductor Nd1.85C0.15CuO4−δ

We report tunneling measurements of the electron-doped superconductor Nd_1.85Ce_0.15Cu0_4–gd using break junctions. The observed finest gap structure is well expressed by the BCS density of states with the energy gap of = 6.1 meV and a very small broadening parameter, having the ratio 2/k_BT_c = 8.2 with T_c = 17.3 K. These features are similar to our tunneling results for the hole-doped cuprate superconductors. Therefore we find no essential difference in the gap structure, in spite of a common believing of the pairingsymmetry difference between them.     

Chemical sensing plate with a laser-terahertz monitoring system

A new type of laser-terahertz emission system for noncontact investigations of chemical solutions has been developed. The system monitors terahertz emission from a sensing plate, which consists of silicon oxide and silicon thin film layers on a sapphire substrate. Sensing of chemical solutions with pH values between 1.68 and 10.01 was demonstrated. The amplitude of the terahertz emission from the sensing plate increased with increasing pH value. This change in the amplitude was caused by a change in the depletion layers of the silicon thin film when protons were adsorbed on the surface of the sensing plate. This study demonstrates that full noncontact monitoring of chemical solutions is possible using the laser-terahertz emission system.