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Journal Articles

Summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident

Iimoto, Takeshi*; Kinoshita, Norikazu*; Sakaguchi, Aya*; Sugihara, Shinji*; Takamiya, Koichi*; Tagami, Keiko*; Nagao, Seiya*; Bessho, Kotaro*; Matsumura, Hiroshi*; Miura, Taichi*; et al.

KEK Report 2016-3, 134 Pages, 2017/03

This report is summary of study on environmental radioactivity effected from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant in 5 years after the accident. It was compiled efforts related to the accident reported from the 13th to the 17th "Workshop on Environmental Radioactivity" which was held at the High Energy Accelerator Research and Development Organization.

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:85.37(Microscopy)

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

Impact of carrier lifetime on efficiency of photolytic hydrogen generation by p-type SiC

Miyake, Keiko*; Yasuda, Tomonari*; Kato, Masashi*; Ichimura, Masaya*; Hatayama, Tomoaki*; Oshima, Takeshi

Materials Science Forum, 778-780, p.503 - 506, 2014/02

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:96.88(Microscopy)

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:55.60(Optics)

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:94.44(Physics, Applied)

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:84.73(Physics, Applied)

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

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:89.85(Microscopy)

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

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

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(Optics)

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

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

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:72.63(Engineering, Biomedical)

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.

Oral presentation

Single flash imaging of live hydrated biological cells by a contact soft X-ray microscope coupled with an intense laser-plasma soft X-ray source

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

no journal, , 

Laser-plasma soft X-ray source produced by a high power pulsed laser is extremely bright and very suitable for biological X-ray microscopy to capture an image of living specimens for which require a single flash exposure to avoid imaging any damages on the specimens. We also have invented to use a fluorescent microscope to identify the cellular organelles in the images obtained with the soft X-ray microscope. The biological cells were cultivated directly onto the PMMA photo resists and observed with the soft X-ray microscope and the fluorescent microscope at the same time. The obtained soft X-ray images and fluorescence images of the cells were directly compared and each cellular organelle such as mitochondria, actin filaments, and chromosomes in the soft X-ray images were clearly identified. Since the soft X-ray microscope has higher spatial resolution than that of the fluorescent microscope, fine structures of the cellular organelles in the hydrated biological cells were observed.

Oral presentation

High contrast imaging with a contact soft X-ray microscope controlling water layer thickness around specimens

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

no journal, , 

Soft X-ray microscope using water window X-ray as light sources has been developed as epoch-making technology to observe living hydrated biological cells with high spatial resolution. Controlling the thickness of water layer is critical to observe living biological cells since the absorption of the soft X-ray by the water layer degrade the cell images. It is important to keep the thickness of the water layer at 5 $$mu$$m to obtain clear cell images. We have designed new silicon nitride windows with spacer and groove structure to keep the water layer thickness at 5 $$mu$$m and have succeeded to obtain high resolution cell images.

Oral presentation

In situ observation of inner structures of biological cells with a soft X-ray microscope

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

no journal, , 

Soft X-ray wavelengths between absorption K-edges of Oxygen and Carbon (2.3 nm and 4.4 nm) are so called "water window" and the X-ray were well absorbed by Carbon and less absorbed by water. Soft X-ray microscope using the water window X-ray as the light source has advantage to be able to observe live biological cells without any artifacts and can observe fine structures of cells compared to the light microscope. Combining with bright and short-pulsed laser-plasma soft X-ray the soft X-ray microscope which named a laser-plasma soft X-ray microscope can observe live biological cells in situ without radiation damages. We have generated bright water window soft X-ray irradiating a high power laser with 1053 nm in wavelength, 20 J in pulse energy and 600 ps in pulse duration onto thin foiled gold targets. Cultivating biological cells directly on the PMMA photoresists in situ observation of live biological cells with the laser-plasma soft X-ray microscope has been realized.

Oral presentation

Intense laser-plasma soft-X-ray sources and its application to biological X-ray microscopy

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

no journal, , 

Soft X-ray microscope has a potential to observe live biological cells. But the cells had to be frozen in order to avoid radiation effects onto the biological cells or to be made a short pulse imaging with an intense X-ray source. Otherwise live cell imaging was not realized. Laser-plasma soft X-ray source was extremely bright and had short pulse duration. Hence it makes possible to capture soft X-ray images of biological cells before the cells damaged. Since the spatial resolution of the soft X-ray microscope depends on the photon flux irradiated onto the samples, it is important to increase brightness of the soft X-ray sources to observe inner structures of biological cells. We have increased the brightness of the soft X-ray source and succeeded in observing inner structures of live biological cells.

Oral presentation

Development of a soft X-ray microscope for direct observation of inner structures of live cells

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

no journal, , 

We have developed a laser-plasma soft X-ray microscope combining an intense short pulsed soft X-ray source to a contact microscopy irradiating the soft X-rays onto cells directly cultivated on an X-ray photo resist and succeeded to observe inner structures of living cells directly. Using a fluorescent microscope with the soft X-ray microscope to observe the same cells at the same time, accurate identification and high resolved observation of cellular organelles have been achieved. Using the laser-plasma soft X-ray microscope inner structure of Leydig cells of mouse testis and structural deformation of apoptotic HeLa S3 nuclei have been observed. Immune cells of mouses have been observed and important structural change at the activation of immune function was found. We have found several important features by observing live cells which were unable by ordinal microscopes.

Oral presentation

Intense laser-plasma soft-X-ray sources and application for biological X-ray microscopy

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

no journal, , 

Although soft X-ray microscope has an ability to observe live biological cells, in order to avoid radiation damages onto the biological cells the cells had to be frozen and live cell imaging was not realized. Since laser-plasma soft X-ray source was extremely bright and had short pulse duration, it makes possible to capture soft X-ray images of biological cells before the cells damaged. Since the spatial resolution of the soft X-ray microscope depends on the photon flux irradiated onto the samples, it is important to increase brightness of the soft X-ray sources to observe inner structures of biological cells. We have increased the brightness of the soft X-ray source and succeeded to observe inner structures of live biological cells.

Oral presentation

Cellular imaging with a laser-plasma soft X-ray microscope

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

no journal, , 

We have developed a laser-plasma soft X-ray microscope composed of an intense short pulsed soft X-ray source and a contact microscopy system in which soft X-rays are irradiating onto biological cells directly cultivated on a recording media, an X-ray photo resist, and succeeded in observing inner structures of living biological cells. Using a fluorescence microscope with the soft X-ray microscope to observe the same biological cells at the same time, accurate identification and high resolved observation of cellular organelles have been achieved such as inner structure of Leydig cells from mouse testis, structural deformation of apoptotic HeLa S3 nuclei and mouse immune cells. In the case of the immune cells we have found structural changes possibly attributed to the activation of immune function.

Oral presentation

Live cell imaging with a soft X-ray microscope using a laser-plasma soft X-ray source

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

no journal, , 

We have developed a laser-plasma soft X-ray microscope composed of an intense short pulsed soft X-ray source and a contact microscopy system in which soft X-rays are irradiating onto biological cells directly cultivated on a recording media, an X-ray photo resist, and succeeded in observing inner structures of living biological cells. Using a fluorescence microscope with the soft X-ray microscope to observe the same biological cells at the same time, accurate identification and high resolved observation of cellular organelles have been achieved such as inner structure of Leydig cells from mouse testis, structural deformation of apoptotic HeLa S3 nuclei and mouse immune cells. In the case of the immune cells we have found structural changes possibly attributed to the activation of immune function.

37 (Records 1-20 displayed on this page)