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Journal Articles

Correlative imaging of live biological cells with a soft X-ray microscope and a fluorescence microscope

Kado, Masataka; Kishimoto, Maki; Tamotsu, Satoshi*; Yasuda, Keiko*; Aoyama, Masato*; Tone, Shigenobu*; Shinohara, Kunio*

AIP Conference Proceedings 1696, p.020019_1 - 020019_4, 2016/01

 Times Cited Count:3 Percentile:85.61

Soft X-ray microscope is a very powerful tool to observe cellular organelles of living biological cells and many works have demonstrated imaging of inner structures of the cells. However the inner structures are very complicated and it is difficult to identify the organelles obtained with the soft X-ray microscopes. We have proposed a hybrid imaging method with a soft X-ray microscope and a fluorescence microscope that is to observe the same biological cells with the both microscopes at the same time. Using the information of the cellular organelles obtained with the fluorescence microscope, inner structures obtained with the soft X-ray microscope are accurately identified. We have observed living biological cells by the hybrid imaging method. Since the soft X-ray microscope has higher spatial resolution than that of the fluorescence microscope, fine structures of the cellular organelles in the living biological cells were discussed.

Journal Articles

In situ observation of cellular organelles with a contact X-ray microscope

Kado, Masataka; Kishimoto, Maki; Tamotsu, Satoshi*; Yasuda, Keiko*; Shinohara, Kunio*

Journal of Physics; Conference Series, 463, p.012056_1 - 012056_4, 2013/10

 Times Cited Count:14 Percentile:96.95

A contact X-ray microscope coupled with a high intense laser plasma soft X-ray source has been developed and in situ observations of cellular organelles have been conducted. The soft X-ray source were generated by a high power laser pulse onto a thin foiled gold target at the photon numbers of 1.3$$times$$10$$^{15}$$ photons/sr to be able to capture an image of live wet biological cells. The cells were cultured on PMMA photoresists that were formed on transparent glass plates to make optical microscope observation possible. The cells were observed by both of optical microscope and soft X-ray microscope. The obtained soft X-ray images were directly compared with corresponding fluorescent optical images. Cellular organelles such as mitochondria and cytoskeleton in the soft X-ray images were identified referencing the information obtained from the fluorescent images.

Journal Articles

Imaging of fine structures of cellular organelles in hydrated biological cells by a soft X-ray microscope combined with a fluorescence microscope

Kado, Masataka; Kishimoto, Maki; Tamotsu, Satoshi*; Yasuda, Keiko*; Aoyama, Masato*; Shinohara, Kunio*

Proceedings of SPIE, Vol.8849, p.88490C_1 - 88490C_7, 2013/09

 Times Cited Count:1 Percentile:55.89

We have proposed to use a fluorescence microscope to identify the cellular organelles in the images obtained with the soft X-ray microscope observing the same cells with both microscopes. The cells were stained with several fluorescent dyes such as Mito-tracker, Phalloidin, and DAPI and after taking many fluorescence images of cellular organelles the cells were exposed to the flash soft X-rays. The obtained soft X-ray images and fluorescence images of the cells were directly compared and each of the cellular organelles such as mitochondria, actin filaments, and chromosomes in the soft X-ray images was clearly identified. Since the soft X-ray microscope has higher spatial resolution than that of the fluorescence microscope, fine structures of the cellular organelles in the hydrated biological cells were observed for the first time.

Journal Articles

Development of single shot soft X-ray contact microscopy system for nano-scale dynamics measurement of living biological specimen

Kishimoto, Maki; Kado, Masataka; Ishino, Masahiko; Tamotsu, Satoshi*; Yasuda, Keiko*; Shinohara, Kunio*

AIP Conference Proceedings 1465, p.43 - 47, 2012/07

 Times Cited Count:9 Percentile:94.57

We have been developing a picosecond single shot soft X-ray contact microscopy system for observing the nanometer-scale inner structure of the living biological specimen in a hydrated condition. The microscopy system consists of an intense IR pump laser system for generating soft X-rays and X-ray microscope chamber. The pump laser system employs OPCPA technique to generate water-window X-rays effectively. The X-ray microscope chamber is composed of a vacuum chamber, a focusing lens, a metal film target, an in-vacuum type sample holder. The soft X-rays from the laser-induced plasma generated by pump laser pulse illuminates bio-specimens on the PMMA photo resist set in the in-vacuum sample holder. The photo resist is developed and the X-ray transmission imageis read out by AFM. We took X-ray images of hydrated Leydig cells from mouse testicle and demonstrated that the developed X-ray microscopy system has a spatial resolution of about 100 nm.

Journal Articles

Observation of organelle by a laser plasma X-ray microscope

Kado, Masataka; Kishimoto, Maki; Ishino, Masahiko; Tamotsu, Satoshi*; Yasuda, Keiko*; Shinohara, Kunio*

AIP Conference Proceedings 1465, p.246 - 250, 2012/07

 Times Cited Count:5 Percentile:85.25

Contact X-ray microscopy has a potential to image wet biological specimens in natural condition. It is very important to identify obtained features in the X-ray images, since X-ray microscopes have potential to image features that have not been visualized yet. We have proposed to compare the X-ray images of the biological specimens with the fluorescence images and to identify the features found in the X-ray images based on the features found in the fluorescence images. Comparing the X-ray images to the fluorescence images of the set biological cells, fine structures of the mitochondria in the X-ray images have been able to be identified.

Journal Articles

A Round robin program of master curve evaluation using miniature C(T) specimens; First round robin test on uniform specimens of reactor pressure vessel materials

Yamamoto, Masato*; Kimura, Akihiko*; Onizawa, Kunio; Yoshimoto, Kentaro*; Ogawa, Takuya*; Chiba, Atsushi*; Hirano, Takashi*; Sugihara, Takuji*; Sugiyama, Masanari*; Miura, Naoki*; et al.

Proceedings of 2012 ASME Pressure Vessels and Piping Conference (PVP 2012) (DVD-ROM), 7 Pages, 2012/07

Master curve (MC) approach for the fracture toughness evaluation is expected to be a powerful tool to assess the structural integrity of reactor pressure vessels (RPVs). In order to get sufficient number of reliable data for the MC approach from broken halves of surveillance test specimens for RPVs, the use of miniature specimens is necessary. For this purpose, a round robin test program on the miniature compact tension specimens (Mini-CT) of 4 mm thick for the MC approach of a Japanese RPV steel has been launched with the participation of academia, industries and a research institute in Japan. The program aims to verify the reliability of experimental data from Mini-CT, and to pick out further investigation items to be solved. As the first step of this program, four institutes carried out MC testing and evaluation using common test procedure and specimens. Valid reference temperature T$$_{0}$$ was successfully obtained in each institute. However, the T$$_{0}$$ values showed large differences with maximum of 34$$^{circ}$$C. It was indicated on the reason of difference that there is a strong correlation between the T$$_{0}$$ values and loading rate, which was selected by each institute per test standard.

Journal Articles

Removal of cesium using cobalt-ferrocyanide-impregnated polymer-chain-grafted fibers

Ishihara, Ryo*; Fujiwara, Kunio*; Harayama, Takato*; Okamura, Yusuke*; Uchiyama, Shoichiro*; Sugiyama, Mai*; Someya, Takaaki*; Amakai, Wataru*; Umino, Satoshi*; Ono, Tsubasa*; et al.

Journal of Nuclear Science and Technology, 48(10), p.1281 - 1284, 2011/10

AA2011-0190.pdf:0.45MB

 Times Cited Count:44 Percentile:94.83(Nuclear Science & Technology)

Journal Articles

Observation of organelles in Leydig cells by contact soft X-ray microscopy with a laser plasma X-ray source

Kado, Masataka; Ishino, Masahiko; Tamotsu, Satoshi*; Yasuda, Keiko*; Kishimoto, Maki; Nishikino, Masaharu; Kinjo, Yasuhito*; Shinohara, Kunio*

AIP Conference Proceedings 1365, p.391 - 394, 2011/09

 Times Cited Count:7 Percentile:89.95

Contact X-ray microscopy has achieved a single-shot imaging of wet biological specimens in natural condition and succeeded in imaging live mouse macrophages with hair-like structures, which was not observed before. It is very important to identify obtained features in the X-ray images, since X-ray microscopes have potential to image features that have not been visualized yet. Here, we demonstrate to image the same biological specimens both by confocal laser microscopy and soft X-ray microscopy. Staining biological specimens with well-established techniques makes easy to identify features in the fluorescence images obtained with confocal laser microscope. Comparing the X-ray images of the specimens with the fluorescence images, features found in the fluorescence images could also be identified in the X-ray images. Comparing the X-ray images to the fluorescence images, fine structures of the actin filaments in the X-ray images were identified.

Journal Articles

Development of a specimen holder combined with ultra thin film laser plasma X-ray source for compact contact-type soft X-ray microscope to observe hydrated living biologocal cells

Ishino, Masahiko; Kado, Masataka; Shinohara, Kunio*; Yamamoto, Yoshimasa*; Hirai, Itaru*; Kishimoto, Maki; Nishikino, Masaharu; Hasegawa, Noboru; Tamotsu, Satoshi*; Yasuda, Keiko*; et al.

Proceedings of SPIE Europe Optics + Optoelectronics 2011, Vol.8139, p.81390R_1 - 81390R_8, 2011/09

 Times Cited Count:0 Percentile:0.01

Ultra thin gold films are favorable laser plasma targets for a soft X-ray microscopy, because the thin films emit intense soft X-rays at the wavelength of water window region. Using rear side emissions, the distance between the X-ray source and the specimens can be reduced so that the X-ray flux on specimens increases. The microscope system can be designed to be compact when the specimen holder and X-ray source are combined in one piece. The biological specimen holder combined with an ultra thin film target has been developed. This X-ray microscope system needs not any X-ray optics which causes a decrease in X-ray photons for imaging. X-ray images of hydrated living cells have been obtained successfully by use of the newly developed specimen holder. Specimen holder combined with plasma X-ray source will be a key component of a compact soft X-ray microscope using in a laboratory.

Journal Articles

Flash imaging of fine structures of cellular organelles by contact X-ray microscopy with a high intensity laser plasma X-ray source

Kado, Masataka; Ishino, Masahiko; Kishimoto, Maki; Tamotsu, Satoshi*; Yasuda, Keiko*; Kinjo, Yasuhito*; Shinohara, Kunio*

Proceedings of SPIE Europe Optics + Optoelectronics 2011, Vol.8139, p.81390O_1 - 81390O_7, 2011/09

Laser plasma X-ray sources have high intensity and short pulse duration, and are suitable for X-ray microscopy in biology. They make wet live biological specimens possible to be imaged with a single shot X-ray exposure and several works have been done to image them. However there were no reports on the imaging of fine structures of cellular organelles in a live biological cell since higher X-ray intensity is needed for it. We have developed a high intensity laser plasma X-ray source, cooperating it with contact X-ray microscopy, and observed fine structures of cellular organelles in a wet biological cells. Comparing the X-ray images and the fluorescence images of cellular organelles such as actin filaments and mitochondria we have been clearly able to identify organelles in the X-ray images and observed fine structures.

Journal Articles

Effect of carbon on irradiation-induced grain-boundary phosphorus segregation in reactor pressure vessel steels using first-principles-based rate theory model

Ebihara, Kenichi; Yamaguchi, Masatake; Nishiyama, Yutaka; Onizawa, Kunio; Matsuzawa, Hiroshi*

Journal of Nuclear Materials, 414(2), p.328 - 335, 2011/07

 Times Cited Count:4 Percentile:32.68(Materials Science, Multidisciplinary)

According to the experiment, the grain-boundary (GB) phosphorus (P) segregation in neutron-irradiated reactor pressure vessel (RPV) steels causes intergranular embrittlement. However the dependence of the segregation on variables such as dose and dose-rate is not clear due to the lack of experimental databases. In this paper, we incorporated the effect of carbon atoms into the rate theory model, and simulated the GB P coverage in the neutron-irradiated RPV steels. As a result, the simulation reproduced the experimental GB P coverage. It was observed that the GB P coverage does not depend on the dose rate regardless of the presence of carbon atoms. Furthermore, it was confirmed that vacancies scarcely transport P atoms to grain-boundaries as compared to the transport by self-interstitial atoms and it was found that carbon atoms influence the irradiation-induced P segregation mainly by suppressing the migration of vacancies.

JAEA Reports

Horonobe Underground Research Laboratory Project; Synthesis of phase I investigation 2001 - 2005, Volume "Geological disposal research"

Fujita, Tomoo; Taniguchi, Naoki; Matsui, Hiroya; Tanai, Kenji; Maekawa, Keisuke; Sawada, Atsushi; Makino, Hitoshi; Sasamoto, Hiroshi; Yoshikawa, Hideki; Shibata, Masahiro; et al.

JAEA-Research 2011-001, 193 Pages, 2011/03

JAEA-Research-2011-001.pdf:5.23MB

This report summarizes the progress of research and development on geological disposal during the surface-based investigation phase (2001-2005) in the Horonobe Underground Research Laboratory project, of which aims are to apply the design methods of geological disposal and mass transport analysis to actual geological conditions obtained from the surface-based investigations in the Horonobe Underground Research Laboratory project as an example of actual geological environment.

Journal Articles

Experimental evidence of nonthermal acceleration of relativistic electrons by an intensive laser pulse

Kuramitsu, Yasuhiro*; Nakanii, Nobuhiko*; Kondo, Kiminori; Sakawa, Yoichi*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; et al.

Physical Review E, 83(2), p.026401_1 - 026401_6, 2011/02

 Times Cited Count:16 Percentile:65.84(Physics, Fluids & Plasmas)

An energy distribution function of energetic particles in the universe or cosmic rays is well represented by a power-law spectrum, therefore, nonthermal acceleration is essential to understand the origin of cosmic rays. A possible candidate for the origin of cosmic rays is wakefield acceleration at relativistic astrophysical perpendicular shocks. Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma.

Journal Articles

Model experiment of cosmic ray acceleration due to an incoherent wakefield induced by an intense laser pulse

Kuramitsu, Yasuhiro*; Nakanii, Nobuhiko*; Kondo, Kiminori; Sakawa, Yoichi*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; et al.

Physics of Plasmas, 18(1), p.010701_1 - 010701_4, 2011/01

 Times Cited Count:19 Percentile:62.63(Physics, Fluids & Plasmas)

Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma. An intensive laser pulse was propagated in a plasma tube created by imploding a hollow polystyrene cylinder, as the large amplitude light waves propagated in the upstream plasma at an astrophysical shock. Nonthermal electrons were generated, and the energy distribution functions of the electrons have a power-law component with an index of 2.

Journal Articles

FIREX project and effects of self-generated electric and magnetic fields on electron-driven fast ignition

Mima, Kunioki*; Sunahara, Atsushi*; Shiraga, Hiroyuki*; Nishimura, Hiroaki*; Azechi, Hiroshi*; Nakamura, Tatsufumi; Jozaki, Tomoyuki*; Nagatomo, Hideo*; Garcia, C.*; Veralde, P.*

Plasma Physics and Controlled Fusion, 52(12), p.124047_1 - 124047_6, 2010/12

 Times Cited Count:9 Percentile:34.11(Physics, Fluids & Plasmas)

Fast ignition is a new scheme in laser fusion, in which higher energy gain with a smaller laser pulse energy is expected. At Osaka University, a laser with four beams and a total output of 10 kJ ps-1, laser for fast ignition experiment (LFEX), has been constructed and we have carried out an integrated experiment with one beam of the LFEX. Through experiments it was found that the coupling efficiency is degraded when the laser pre-pulse is not sufficiently small. Furthermore, the distance between the hot electron source and the core plasma is large. In this paper it is proposed that a thin foil covers the laser entrance of the cone to mitigate the pre-plasma and a double cone reduces the loss of high energy electrons from the side wall of the cone. The simulations indicate that a higher coupling efficiency is expected for the double cone target with a thin foil at the laser entrance.

Journal Articles

Observation of actin filaments in Leydig cells with a contact-type soft X-ray microscope with laser plasma X-ray source

Kado, Masataka; Ishino, Masahiko; Tamotsu, Satoshi*; Yasuda, Keiko*; Kishimoto, Maki; Nishikino, Masaharu; Kinjo, Yasuhito*; Shinohara, Kunio*

Denki Gakkai Rombunshi, C, 130(10), p.1774 - 1778, 2010/10

Actin filaments in Leydig cells from mouse testes have been observed with a contact-type soft X-ray microscope with laser plasma X-ray source. The Leydig cells were fixed with paraformaldehyde, stained with Phalloidin, and observed with a confocal laser microscope prior to the observation with X-ray microscope. Obtained images by both of the confocal laser microscopy and the X-ray microscopy were directly compared and revealed that not only position of actin filaments but also the shapes can be identified each other. The actin filaments in the X-ray images were clearly recognized and their structures were obtained in more detail compared to those in the confocal laser microscope images.

Journal Articles

Evaluation of residual stress distribution due to welding and surface machining and crack growth behavior

Ihara, Ryohei*; Hashimoto, Tadafumi*; Mikami, Yoshiki*; Katsuyama, Jinya; Onizawa, Kunio; Mochizuki, Masahito*

Nihon Hozen Gakkai Dai-7-Kai Gakujutsu Koenkai Yoshishu, p.611 - 616, 2010/07

In light-water reactor nuclear power stations, stress corrosion cracking (SCC) has been observed near the welded joint in recirculation piping made of low-carbon austenitic stainless steel. Residual stress is one of the most important factors in the occurrence and propagation of SCC. The joining process of pipes which usually consists of surface machining and welding results in high tensile residual stress. In this study, finite element analysis method was developed to evaluate residual stress generated by surface machining considering the shape of machining tool and machining condition. Residual stress due to surface machining was measured by X-ray diffraction method and analysed the method developed. It was shown that high tensile residual stress due to machining occurred very limited surface region. It was also shown that surface machining affected SCC growth behavior significantly from the SCC analysis results based on residual stress distributions due to surface machining and welding.

Journal Articles

Observations of the intense soft X-ray emissions from ultra thin Au films irradiated with high contrast laser pulses

Ishino, Masahiko; Kado, Masataka; Nishikino, Masaharu; Shinohara, Kunio*; Tamotsu, Satoshi*; Yasuda, Keiko*; Hasegawa, Noboru; Kishimoto, Maki; Oba, Toshiyuki; Kawachi, Tetsuya

Proceedings of SPIE, Vol.7589, p.75891B_1 - 75891B_8, 2010/02

 Times Cited Count:2 Percentile:72.88

Soft X-ray microscopes operating in the water window are capable of imaging living hydrated biological specimens. Laser produced plasmas are attractive soft X-ray sources, because of their short duration time. Based on the minimum dose calculation, soft X-ray photons more than 10$$^{5}$$ photons/$$mu$$m$$^{2}$$ at the sample surface are needed to acquire an image of the biological specimens with spatial resolution up to 100 nm. The observations of soft X-ray emissions from laser produced plasmas using ultra thin film targets have been carried out. Au thin films were irradiated by a high contrast Nd:glass laser pulses. The spectral properties of emitted soft X-rays were monitored by an X-ray spectrograph from the rear side with respect to the surface of laser irradiation. The observed emission intensities had an obvious dependence on the film thickness, and the most intense emissions were obtained at the thickness of 28 nm. The experimental results have suggested that the most of the laser energy irradiated is absorbed by the film target, and it is resulted an efficient energy deposition from laser to X-rays.

Journal Articles

Numerical simulation of residual stress distribution generated by machining and the effect on crack growth

Ihara, Ryohei*; Katsuyama, Jinya; Onizawa, Kunio; Hashimoto, Tadafumi*; Mikami, Yoshiki*; Mochizuki, Masahito*

Yosetsu Kozo Shimpojiumu 2009 Koen Rombunshu, p.393 - 396, 2009/11

Stress Corrosion Cracking (SCC) has been observed near the weld zone of the primary loop recirculation pipes made of SUS316L. For the evaluation of initiation and propagation of SCC for non-sensitization material, residual stress distribution generated by surface-machining is the most important factors. In this study, residual stress distributions generated are evaluated by varying cutting speed, and crack growth analysis are performed using evaluated residual stress distributions. As a result, crack growth highly depends on residual stress distributions by surface-machining.

Journal Articles

A Study of redistribution of residual stress and hardness due to welding and surface-machining at girth welded joint

Mochizuki, Masahito*; Katsuyama, Jinya; Ihara, Ryohei*; Mori, Hiroaki*; Mikami, Yoshiki*; Onizawa, Kunio

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07

Stress corrosion cracking near the welded zone of core internals and recirculation piping has been observed at the surface where tensile residual stress exists due to welding and/or surface machining. The tensile residual stress in the inner surface of the pipe is caused by welding and surface machining. In this study, Vickers hardness and residual stress distributions at the inner surface of butt-weld joint with surface-machining before and after welding were experimentally evaluated. Welding simulation has been performed to study the distribution and the occurrence mechanism of tensile residual stress. It was shown that residual stress and hardness distributions by welding after surface machining depended on the welding condition and that the effect of surface machining disappeared. Residual stress distributions due to surface-finishing after welding were also found to depend on surface-machining condition but the region was limited to a thin area of surface hardened layer.

102 (Records 1-20 displayed on this page)