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Phonon echoes in Si:P at very low temperature
Jeong, M,Song, M,Ueno, T,Mizusaki, T,Matsubara, A,Lee, S Institute of Physics 2009 Journal of physics. Conference series Vol.150 No.4
<P>We observed phonon echoes in P-doped Si (Si:P) at very low temperatures. We applied two radio-frequency pulses separated by a time delay of τ on Si:P and observed echo signal at <I>t</I> &equal; 2τ in both insulating and metallic samples with varying dopant concentrations and of different sample forms of powders and bulk plates at temperature between 45 mK and 4 K. The echoes were much more pronounced in insulating powder samples than in metallic ones and in bulk ones. The echo intensity for a fixed τ increased very strongly as temperature was lowered but the echoes disappeared toward the superfluid-to-normal transition temperature of helium mixture in which the samples were immersed. We observed no appreciable change in the echo intensities as external magnetic field was varied up to 8 T. The echoes are interpreted to be dynamical polarization phonon echoes in piezoelectric powders of insulating Si:P with a dopant concentration <I>n</I> &equal; 6 x 10<SUP>17</SUP> cm<SUP>-3</SUP>.</P>
( T. Igarashi ),( A. Komatsu ),( T. Motooka ),( F. Ueno ),( M. Yamamoto ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.3
In oxidizing nitric acid solutions, stainless steel undergoes intergranular corrosion accompanied by grain dropping and changes in the corrosion rate. For the safe operation of reprocessing plants, this mechanism should be understood. In this study, we constructed a three-dimensional computational model using a cellular automata method to simulate the intergranular corrosion propagation of stainless steel. The computational model was constructed of three types of cells: grain (bulk), grain boundary (GB), and solution cells. Model simulations verified the relationship between surface roughness during corrosion and dispersion of the dissolution rate of the GB. The relationship was investigated by simulation applying a constant dissolution rate and a distributed dissolution rate of the GB cells. The distribution of the dissolution rate of the GB cells was derived from the intergranular corrosion depth obtained by corrosion tests. The constant dissolution rate of the GB was derived from the average dissolution rate. Surface roughness calculated by the distributed dissolution rates of the GBs of the model was greater than the constant dissolution rates of the GBs. The cross-sectional images obtained were comparable to the corrosion test results. These results indicate that the surface roughness during corrosion is associated with the distribution of the corrosion rate.
Tanaka, T.,Abe, K.,Hayato, Y.,Iida, T.,Kameda, J.,Koshio, Y.,Kouzuma, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Obayashi, Y.,Sekiya, H.,Shiozawa, M.,Suzuki, Y.,Takeda, A.,Takenaga, Y.,Ueno, IOP Publishing 2011 The Astrophysical journal Vol.742 No.2
<P>We present the result of an indirect search for high energy neutrinos from Weakly Interacting Massive Particle (WIMP) annihilation in the Sun using upward-going muon (upmu) events at Super-Kamiokande. Data sets from SKI-SKIII (3109.6 days) were used for the analysis. We looked for an excess of neutrino signal from the Sun as compared with the expected atmospheric neutrino background in three upmu categories: stopping, non-showering, and showering. No significant excess was observed. The 90% C. L. upper limits of upmu flux induced by WIMPs of 100 GeV c(-2) were 6.4 x 10(-15) cm(-2) s(-1) and 4.0 x 10(-15) cm(-2) s(-1) for the soft and hard annihilation channels, respectively. These limits correspond to upper limits of 4.5 x 10(-39) cm(-2) and 2.7 x 10(-40) cm(-2) for spin-dependent WIMP-nucleon scattering cross sections in the soft and hard annihilation channels, respectively.</P>
Nishiguchi, T.,Cho, K.,Yasutomi, M.,Ueno, M.,Yamaguchi, K.,Basti, L.,Yamasaki, Y.,Takeshita, S.,Kim, D.,Oda, T. Elsevier/North Holland Biomedical Press 2016 Aquatic toxicology Vol.179 No.-
<P>A harmful dinoflagellate, Heterocapsa circularisquama, is highly toxic to shellfish and the zooplankton rotifer Brachionus plicatilis. A previous study found that H. circularisquama has both light-dependent and -independent haemolytic agents, which might be responsible for its toxicity. Detailed analysis of the haemolytic activity of H. circularisquama suggested that light-independent haemolytic activity was mediated mainly through intact cells, whereas light-dependent haemolytic activity was mediated by intracellular agents which can be discharged from ruptured cells. Because H. circularisquama showed similar toxicity to rotifers regardless of the light conditions, and because ultrasonic ruptured H. circularisquama cells showed no significant toxicity to rotifers, it was suggested that live cell-mediated light-independent haemolytic activity is a major factor responsible for the observed toxicity to rotifers. Interestingly, the ultrasonic-ruptured cells of H. circularisquama suppressed their own lethal effect on the rotifers. Analysis of samples of the cell contents (supernatant) and cell fragments (precipitate) prepared from the ruptured H. circularisquama cells indicated that the cell contents contain inhibitors for the light-independent cell-mediated haemolytic activity, toxins affecting H. circularisquama cells themselves, as well as light-dependent haemolytic agents. Ethanol extract prepared from H. circularisquama, which is supposed to contain a porphyrin derivative that displays photosensitising haemolytic activity, showed potent toxicity to Chattonella marina, Chattonella antiqua, and Karenia mikimotoi, as well as to H. circularisquama at the concentration range at which no significant toxicity to rotifers was observed. Analysis on a column of Sephadex LH-20 revealed that light-dependent haemolytic activity and inhibitory activity on cell-mediated light-independent haemolytic activity existed in two separate fractions (f-2 and f-3), suggesting that both activities might be derived from common compounds. Our results suggest that the photosensitising haemolytic toxin discharged from ruptured H. circularisquama cells has a relatively broad spectrum of phytoplankton toxicity, and that physical collapse of H. circularisquama cells can lead not only to the disappearance of its own toxicity, but also to mitigation of the effects of other HABs. (C) 2016 Elsevier B.V. All rights reserved.</P>
Tsukamoto,T. Ueno,K. Yamamoto,Y. Ohbuchi,H. Sakamoto 한국공학교육학회 2010 공학교육연구 Vol.13 No.2
It is necessary for lower grade students to study the correct usage of tools as a base of the technical education for dismantling and assembling various machines. However, enough understanding has not been obtained though the usage of these tools when training first grade students. So, we started to develop a teaching text and materials within the students practice curriculum based on the dismantling and assembly of all-terrain vehicle [ATV] s, which is a very motivating for lower grade students. This practice makes the student learn both how to use the tools and the steering mechanism of cars through the dismantling and assembling of the ATV. It is possible to not only have the student learn about the knowledge obtained through the practice, but also they also acquire wider and deeper knowledge through making the text and teaching materials for the practice. The textbook and secondary educational materials of this practice curriculum were created in cooperation with a fifth grade student as part of their graduation research. As a result, an effective teaching and learning text and secondary educational material regarding manufacturing practice could be developed from the student s point of view. Making a teaching text and materials is effective for promoting the study and experience of engineering.
K. Tsukamoto,T. Ueno,K. Yamamoto,Y. Ohbuchi,H. Sakamot 한국공학교육학회 2010 공학교육연구 Vol.13 No.2
It is necessary for lower grade students to study the correct usage of tools as a base of the technical education for dismantling and assembling various machines. However, enough understanding has not been obtained though the usage ofthese tools when training first grade students. So, we started to develop a teaching text and materials within the students'practice curriculum based on the dismantling and assembly of all-terrain vehicle [ATV]'s, which is a very motivating forlower grade students. This practice makes the student learn both how to use the tools and the steering mechanism of carsthrough the dismantling and assembling of the ATV. It ispossible to not only have the student learn about the knowledgeobtained through the practice, but also they also acquire wider and deeper knowledge through making the text and teachingmaterials for the practice. The textbook and secondary educational materials of this practice curriculum were created in cooperation with a fifth grade student as part of their graduation research. As a result, an effective teaching and learningtext and secondary educational material regarding manufacturing practice could be developed from the student's point ofview. Making a teaching text and materials is effective for promoting the study and experience of engineering
INFRARED AND OPTICAL IMAGINGS OF THE COMET 2P/ENCKE DUST CLOUD IN THE 2003 RETURN
Sarugaku, Yuki,Ishiguro, Masateru,Ueno, Munetaka,Usui, Fumihiko,Reach, William T. IOP Publishing 2015 The Astrophysical journal Vol.804 No.2
<P>We report contemporaneous imaging observations of the short-period comet 2P/Encke in infrared and optical wavelengths during the 2003 return. Both images show the same unique morphology consisting of a spiky dust cloud near the nucleus and a dust trail extending along the orbit. We conducted a dynamical simulation of dust particles to characterize the morphology and found that dust particles were ejected intensively for a short duration (less than or similar to 10 days) a few days after perihelion passage. The maximum particle size is at least on the order of 1 cm in radius following a differential power-law size distribution with an index of -3.2 to -3.6. The total mass ejected in the 2003 return is at least 1.5 x 10(9) -1.2 x 10(10) kg, which corresponds to 0.003%-0.03% of the nucleus mass. We derived the albedo of the dust cloud as 0.01-0.04 at a solar phase angle of 26 degrees. 2, which is consistent with or possibly greater than that of the nucleus. We suppose that impulsive activity such as an outburst is a key to understanding the peculiar appearance of 2P/Encke.</P>