Point-Focusing Electromagnetic-Acoustic Transducer for Crack Inspection

Stress corrosion cracking in stainless-steel pipes is a critical failure in atomic power plants and chemical plants. In ultrasonic testing, piezoelectric transducers are generally used, in which reproducibility of amplitude measurements is not necessarily high because of effects of coupling materials and contacting conditions between the transducers and specimens. Comparing to the transducers, an electromagnetic acoustic transducer (EMAT) requires no coupling materials and is less sensitive to the contacting conditions, making the reproducibility higher. However, lower signal to noise (S/N) ratio has been a disadvantage. For increasing the S/N ratio, we developed a point-focusing EMAT (PF-EMAT) [1]. It generated shear-vertical (SV) waves from concentric line sources on a top surface of a specimen. Coil configuration of the EMAT was designed so that the SV waves were accumulated in phase at a focal point on the bottom surface, which increased the S/N ratio and improved the spatial resolution. We have designed PF-EMATs operated at different frequencies, and applied to artificially fabricated defects on stainless steel specimens. In this presentation, we show the results, and discuss availability of the PF-EMAT to crack inspection

Deep-Learning-Assisted Resonant Ultrasound Spectroscopy for Cubic Solids

This paper solves a long-standing problem in resonant ultrasound spectroscopy (RUS) for cubic solids through the use of two-dimensional deep learning (DL). By means of inverse methods, conventional RUS can determine all independent elastic constants of a crystalline solid specimen by comparing measured and calculated free-vibration resonance frequencies. However, to avoid invalid local minima in the inverse process, good initial guesses of the elastic constants must be available. Here, we propose a DL scheme to remedy this problem, which utilizes an input elasticity image composed of three layers obtained from resonance frequency data. After network training, this scheme is executed in two steps: DL processing by a neural network to output elastic constants in a Blackman diagram classification, followed by the use of a regression network around the classified point in this diagram for more accurate determination. By means of simulations, we demonstrate that this DL scheme yields the principal elastic constants within an error of approximately 5% without any inverse processing even in the unfavorable case of five missing modes for 111 existing cubic crystals.Fukuda Hiroki, Nagakubo Akira, Wright Oliver B., et al. Deep-Learning-Assisted Resonant Ultrasound Spectroscopy for Cubic Solids. Physical Review Applied 20, 228 (2023); https://doi.org/10.1103/physrevapplied.20.034048

Novel Oral Derivative UD-017, a Highly Selective CDK7 Inhibitor, Exhibits Anticancer Activity by Inducing Cell-Cycle Arrest and Apoptosis in Human Colorectal Cancer

Objective: This study aimed to investigate the anticancer profile of a new cyclin-dependent kinase 7 (CDK7) inhibitor, UD-017, by examining its mechanism of action using HCT-116 colorectal cancer cells. Methods: The anticancer properties of UD-017 were assessed using several assays, including in vitro kinase, proliferation, and apoptosis assays, western blot analysis, and an in vivo xenograft mouse model. Results: UD-017 significantly inhibited CDK7 activity (IC50 = 16 nM) with high selectivity in an in vitro kinase assay testing a panel of over 300 proteins and lipid kinases. UD-017 also inhibited the growth of HCT-116 cells (GI50 = 19 nM) and inhibited the phosphorylation of various downstream mediators of CDK7 signaling. In cell cycle and apoptosis assays using HCT-116 cells, UD-017 increased the number of cells in both G1 and G2/M phases and induced apoptosis. In vivo, UD-017 inhibited tumor growth in an HCT-116 xenograft mouse model by 33%, 64%, and 88% at doses of 25, 50, and 100 mg/kg, respectively, with clear dose-dependency. Co-administration of 5-FU and 50 mg/kg UD-017 had a strong synergistic effect, as reflected in the complete inhibition of tumor growth. Conclusion: CDK7 may play a major role in colorectal cancer growth by regulating the cell cycle and apoptosis. UD-017 is a promising candidate therapeutic agent for the treatment of cancer involving CDK7 signaling

The ASTRO-H X-ray Observatory

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

Hitomi (ASTRO-H) X-ray Astronomy Satellite

The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E  >  2  keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month

Recent Breakdown of the Seasonal Linkage between the Winter North Atlantic Oscillation/Northern Annular Mode and Summer Northern Annular Mode

The summer northern annular mode (NAM) and the winter North Atlantic Oscillation (NAO)/winter NAM have a positive correlation from the mid-1960s to the 1980s. Namely, when the winter NAO/NAM is in a positive phase, the following summer NAM tended to be in a positive phase. During the period from the mid-1960s to the 1980s, the NAO/NAM signals extended to the stratosphere in winter. Also, the lower-tropospheric warm anomaly over northern Eurasia in winter associated with the positive phase of NAO/NAM continued into spring. In summer, the annular anomalies in the temperature and 500-hPa height fields appeared, and the high-latitude westerly wind was enhanced following the winter positive NAO/NAM. However, after circa 1990, the seasonal linkage was broken (i.e., the winter-to-summer correlation became insignificant). The stratospheric signal in the winter NAO/NAM became weak and summer signals associated with the winter NAO/NAM almost disappeared. Seasonal evolutions of atmospheric circulation and sea surface temperature (SST) anomalies associated with the winter NAO are examined for an early good-linkage period and a recent poor-linkage period. We discuss the possible causes of the linkage breakdown such as stratospheric ozone, North Atlantic SST, and Atlantic multidecadal oscillation, besides chaotic internal variability in the climate system. Simulations with the Community Earth System Model suggest that the ocean and/or sea ice with interseasonal memories possibly cause the linkage, besides large internal variability through which the linkage can take place by chance

Development of shear-vertical-wave point-focusing electromagnetic acoustic transducer

A shear-vertical-wave point-focusing electromagnetic acoustic transducer is developed for the purpose of detecting stress corrosion cracking in stainless steel. The transducer is composed of a permanent magnet and two identical concentric meander-line coils, one for the transmitter and the other for the receiver, and the shear-vertical waves are excited and detected by the Lorentz force mechanism. The meander-line coils are designed so that the phases of all the excited shear-vertical waves are focused in phase at a focal point. The focal area is evaluated experimentally, and it is confirmed that the developed transducer is capable of detecting slit defects deeper than 0.05mm at the bottom surface of a stainless-steel plate 20mm thick.Takashi Takishita, Kazuhiro Ashida, Nobutomo Nakamura, Hirotsugu Ogi and Masahiko Hirao. Development of shear-vertical-wave point-focusing electromagnetic acoustic transducer. Japanese Journal of Applied Physics, 2015, 54,(7S1), 07HC04. https://doi.org/10.7567/JJAP.54.07HC04