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Abstract: We have successfully fabricated novel microscopic imaging devices made from UV/EB curable resin using an external scanning proton microbeam. The devices are micro-structured fluorescent plates that consist of an array of micro-pillars that align periodically. The base material used in the pillars is UV/EB curable resin and each pillar contains phosphor grains. The pattern exposures were performed using a proton beam writing technique. The height of the pillars depends on the range of the proton beam. Optical microscopy and scanning electron microscopy have been used to characterize the samples. The results show that the fabricated fluorescent plates are expected to be compatible with both spatial resolution and detection efficiency. [Copyright &y& Elsevier]

Abstract: The neutron-capture cross-section of Gd2O2S:Tb scintillators is considerably higher than that of ZnS/LiF scintillators, which are commonly used in neutron radiography. The characteristics of these powder-type Gd2O2S:Tb scintillators correlate to some material parameters, including scintillator layer thickness and powder size. Three types of Gd2O2S:Tb scintillators with different powder particle sizes were prepared, and the effects of the powder size and scintillator layer thickness on the scintillator characteristics were evaluated using a sensitivity indicator (SI) and a beam purity indicator (BPI). The intensity of scintillation increased as the particle size increased. In addition, the intensity of scintillation detected saturated at a specific thickness for each scintillator particle size. This saturation was considered to be caused by differences in the packing rate of the powder near the substrate and the flight paths of thermal neutrons and internal conversion electrons in the scintillator. Additionally, the image quality worsened with increasing scintillator layer thickness. On the basis of our investigation, we determined the optimum powder particle size and layer thickness of the Gd2O2S:Tb scintillator for neutron imaging. [Copyright &y& Elsevier]

Abstract: Neutron radiography is one of the useful tools for visualizing water behavior in operating fuel cells. In order to observe the detailed information about the water distribution in membrane electrode assembly (MEA) and gas diffusion layer (GDL) in fuel cells, a high performance neutron imaging system is required. A neutron color image intensifier (NCII) is a high spatial resolution and high sensitivity neutron image detector. We have developed an imaging system using an NCII for visualizing the behavior of water in fuel cells. The pixel size of the imaging system is around 4.7μm in the small view field. By using this system, water distribution of a small sized fuel cell was observed continuously every 20s at the Thermal Neutron Radiography Facility (TNRF). In the results, the water area appears from the GDL and MEA regions, and expanded to the cathode side channel with time. However, the voltage was gradually reduced with time, and steeply dropped. It is considered that the reduction and the drop of voltage were caused by a blockage of gas flow due to accumulation of water in the GDL and the gas flow channel in the cathode side. [Copyright &y& Elsevier]

Abstract: Distributions of hydrogen isotope concentrations in ε-phase zirconium hydrides and deuterides (ε-ZrH x and ε-ZrD x : 1.8< x <2.0) were investigated by neutron radiography (NRG). The NRG images of the thermal neutron transmission and backscattering revealed hydrogen concentration dependence and isotope differences. The thermal neutron mass attenuation coefficients in relation to the hydrogen isotope concentrations were determined from the transmission NRG images. The results showed the isotope effects of the thermal neutron mass attenuation coefficients for ε-ZrH x to be about 6–9 times higher than those for ε-ZrD x . The neutron scattering processes for transmission and backscattering NRG images of ε-ZrH x and ε-ZrD x were also analyzed using a general Monte Carlo neutron-particle transport (MCNP) code. [Copyright &y& Elsevier]

Advanced neutron radiography techniques such as the neutron imaging plate (NIP) and neutron computed tomography (NCT) methods have been investigated in the practicability for the postirradiation examination (PIE). In current works, an unirradiated fuel rod was examined by NIP and NCT methods in order to collect the fundamental data for applying these techniques to the PIE. A fuel rod used is composed of seven-enriched UO2 and two-natural UO2 pellets with controlled sizes and shape that are loaded into a Zircaloy tube. The neutron radiography tests were performed by NIP and NCT methods at the 2nd Thermal Neutron Radiography Facility (TNRF-2) in the Japan Research Reactor (JRR)-3. In the NIP image of the fuel rod, the difference in the size, shape, and enrichment between the UO2 pellets is obviously recognized. In the case of NCT method, the images clearly show the detailed shape of the cross section in both enriched and natural pellets; and difference in the enrichment between those pellets is also observed. In addition, size difference between fuel parts of specifications and those in NCT images is evaluated. [ABSTRACT FROM AUTHOR]

Abstract: Proton beam writing is a direct-write technique and a promising method for the micromachining of commodity plastics such as acrylic resins. Herein, we describe the fabrication of microscopic devices made from a relatively thick (∼75μm) acrylic sheet using proton beam writing. In addition, a software package that converts image pixels into coordinates data was developed, and the successful fabrication of a very fine jigsaw puzzle was achieved. The size of the jigsaw puzzle pieces was 50×50μm. For practical use, a prototype of a line and space test-chart was also successfully fabricated for the determination of spatial resolution in neutron radiography. [Copyright &y& Elsevier]

Purpose To create a reproducible canine model of giant aneurysms. Materials and methods Seven mongrel dogs were used for this study. All procedures were performed under an institutional approved protocol. Anesthesia was induced with propofol 10 mg/kg intravenous injection, and maintained using 1–5% isoflurane and 100% oxygen. After the neck was sterilely prepped and draped, bilateral 10 cm incisions were made medial to each external jugular vein. 30 mm segments of both external jugular veins were ligated, removed and placed in heparinized saline (1000 U heparin/100 ml saline). The left common carotid artery (CCA) was ligated proximally and a temporary vascular clamp was placed distally. A tunnel was created under the trachea to pass the left CCA to the right side. Temporary clamps were placed proximally and distally on the right CCA. An 8 mm arteriotomy was made on the right CCA midway between the clamps. The distal segment of the left CCA was then anastomosed to the base of the right CCA. Both external jugular vein segments were opened longitudinally and angled (arrowhead shaped) incisions were made into both vein segments so that they would match the arterial opening where the right and left CCAs had been anastomosed. The opened segments of the jugular veins were then anastomosed to form a single cylinder using a running suture technique. Once this was done the resulting vein pouch was sewn into the opening between the right and left CCA. All vascular sutures were performed using 7-0 prolene suture. The temporary vascular clamps were removed, and if any leaks were seen, additional sutures were used until hemostasis was established (). Incisions were closed using absorbable suture. The surgical procedure took 2.5 h. Animals were allowed to recover for further studies. Angiograms were preformed 4.5 weeks after the aneurysm creation. Results Six of seven aneurysms remained fully patent 4.5 weeks post-creation (). During this interval, animals showed no surgical related complications. No medication was needed to prevent thrombus. Aneurysm dimensions are shown in Abstract P-010 . Aneurysm dimensions Conclusion We successfully developed a reproducible giant aneurysm model using a vein patch technique. [ABSTRACT FROM PUBLISHER]

Abstract: A multi-pinhole collimator system, which is effective for enlarging imaging area with high spatial resolution, has been demonstrated on Cold Neutron Radiograph Facility at JRR-3M in JAEA. The multi-pinhole collimator system consists of a multi-pinhole aperture and an overlap-cutter. On neutron beam from the multi-pinhole aperture, neutrons from each pinhole overlap at the sample position due to beam divergence. In the overlap area, sample images from each pinhole are obtained at a detector and these images look like split images. The overlap-cutter works to cut neutrons contribute to overlap at sample position and enable us to get an image without split. Imaging area was enlarged and sharp image without split was successfully obtained by using the multi-pinhole collimator system. [Copyright &y& Elsevier]

Metabotropic glutamate 1 (mGlu) receptor has been proposed as a target for the treatment of metastatic melanoma. Studies have demonstrated that inhibiting the release of glutamate (the natural ligand of mGlu1 receptors), results in a decrease of melanoma tumor growth in mGlu1 receptor-expressing melanomas. Here we demonstrate that mGlu1 receptors, which have been previously characterized as oncogenes, also behave like dependence receptors by creating a dependence on glutamate for sustained cell viability. In the mGlu1 receptor-expressing melanoma cell lines SK-MEL-2 (SK2) and SK-MEL-5 (SK5), we show that glutamate is both necessary and sufficient to maintain cell viability, regardless of underlying genetic mutations. Addition of glutamate increased DNA synthesis, whereas removal of glutamate not only suppressed DNA synthesis but also promoted cell death in SK2 and SK5 melanoma cells. Using genetic and pharmacological inhibitors, we established that this effect of glutamate is mediated by the activation of mGlu1 receptors. The stimulatory potential of mGlu1 receptors was further confirmed in vivo in a melanoma cell xenograft model. In this model, subcutaneous injection of SK5 cells with short hairpin RNA-targeted downregulation of mGlu1 receptors resulted in a decrease in the rate of tumor growth relative to control. We also demonstrate for the first time that a selective mGlu1 receptor antagonist JNJ16259685 ((3,4-Dihydro-2H-pyrano[2,3-b]quinolin-7-yl)-(cis-4-methoxycyclohexyl)-methanone) slows SK2 and SK5 melanoma tumor growth in vivo. Taken together, these data suggest that pharmacological inhibition of mGlu1 receptors may be a novel approach for the treatment of metastatic melanoma. [ABSTRACT FROM AUTHOR]

Abstract: Fuel gas (hydrogen gas) and oxidant gas (air) are supplied to a polymer electrolyte fuel cell (PEFC). Protons pass through the electrolyte membrane, and combine with oxygen to form water in the cathode reaction site. The generated water must be supplied appropriately to the membrane for proton conduction. On the other hand, the generated water may affect the fuel cell performances because of the blocking of oxygen from reaching the cathode reaction site. Therefore, water management in the PEFC is important, and water distribution during the operation in the through-plane direction has been of wide concern. In order to obtain the water distributions in a membrane electrode assembly (MEA) and a gas diffusion layer (GDL), a borescope system was newly employed using neutron radiography. The system could obtain the water distribution in the MEA and the GDL, and pixel size of 6.5μm was achieved. Furthermore, the system was applied for a tilted converter system. The pixel of 1.0μm at an angle of 81° was achieved, and improvement of the spatial resolution was confirmed. [Copyright &y& Elsevier]

Abstract: Visualization of dynamic three-dimensional water behavior in a polymer electrolyte fuel cell (PEFC) stack was carried out by neutron CT using a neutron image intensifier. The neutron radiography system at JRR-3 in Japan Atomic Energy Agency was used. An operating stack with three cells based on Japan Automobile Research Institute standard was visualized. A consecutive CT reconstruction method by rotating the fuel stack continuously was developed using a neutron image intensifier and a C-MOS high speed video camera. The dynamic water behavior in channels in the operating PEFC stack was clearly visualized in 15s intervals by the present dynamic neutron CT system. [Copyright &y& Elsevier]

Abstract: Neutron imaging by color center formation in LiF crystals was applied to a sensitivity indicator (SI) as a standard samples for neutron radiography. The SI was exposed to a 5mm pinhole-collimated thermal neutron beam with an LiF crystal and a neutron imaging plate (NIP) for 120min in the JRR-3M thermal neutron radiography facility. The image in the LiF crystal was read out using a laser confocal microscope. All gaps were clearly observed in images for both the LiF crystal and the NIP. The experimental results showed that LiF crystals have excellent characteristics as neutron imaging detectors in areas such as high spatial resolution. [Copyright &y& Elsevier]

Abstract: In order to clarify the effects of water on performances of a Polymer Electrolyte Fuel Cell (PEFC), measurements of water distribution in a Japan Automobile Research Institute (JARI) standard PEFC were carried out by means of neutron radiography. Furthermore, the cell voltage and the pressure drop between inlet and outlet of the air were simultaneously measured. The effects of channel geometry, i.e. single-serpentine and three-serpentine, and relative humidity of air were investigated. The experimental conditions were current density of 200mA/cm2, hydrogen utilization of 9.5% and oxygen utilization of 40%. The membrane electrode assembly (MEA) area was 5×5cm2. The pictures were taken every 15s with an exposure time of 12s. The spatial resolution was 108μm. From the measurements, the relation between cell voltage, pressure drop and movement of the water plug in the channel was confirmed. The PEFC performances were recovered as the water plug evacuated. Condensed water in the channel decreased with the relative humidity of air. However, it may affect the MEA permanence. Therefore, the most appropriate operating conditions should be decided for taking into account both the cell performances and the permanencies. [Copyright &y& Elsevier]

We carried out experiments of U(VI) uptake by fluorapatite (FAp) plate samples with a U(VI) concentration of 4.0×10-4 mol·l-1, at final pHs ranging from 2.3 to 4.0 and at 25 °C to elucidate U(VI) uptake mechanisms. The U(VI) uptake by FAp increased with decreasing pH, which is in contrast with typical cation uptake by minerals where adsorption increases with increasing pH. Although the solutions were undersaturated with respect to autunite, Ca(UO2)2(PO4)2⋅nH2O, a layer of autunite was in the FAp leached layer. If we assumed that pH was 1.3 times higher or U(VI) or P concentration was 40 times higher locally than the respective observed values in the bulk solutions, the local solutions were calculated to be supersaturated with respect to autunite. Our results strongly suggest that autunite formation is caused by local saturation in the leached layer even when a bulk solution is undersaturated with respect to autunite. Rutherford backscattering spectrometry (RBS) revealed that the thickness of the autunite layer increased with decreasing pH or with increasing time, i.e., with increasing dissolution of FAp, and that the concentration of U in the autunite layer was not significantly changed with time at constant pH. These indicate that the autunite layer becomes thicker without increasing the distribution density of autunite in the autunite layer as the reaction proceeds. RBS also revealed that a leached layer of FAp, where FAp was dissolving, was present between fresh FAp and the autunite layer, and characterized by a lower U concentration than that in the autunite layer and by higher and lower Ca concentrations than those in the autunite layer and FAp, respectively. Our results by RBS strongly suggest that the surface mineralization proceeds in the leached layer by local saturation and that autunite formed is finally added to and accumulated in the autunite layer. The surface mineralization in the leached layer explains the concurrent increases in U(VI) uptake, autunite-layer thickness and dissolution of FAp with decreasing pH or with increasing reaction time. Uranium(VI) uptake experiments were separately carried out on FAp powder samples with U(VI) concentrations of 4.0×10-4 and 4.0×10-6 mol·l-1, which resulted in autunite precipitation and U(VI) adsorption, respectively, for the uptake mechanisms. Surface mineralization should be taken into account for remediation and radioactive waste disposal in addition to adsorption and precipitation. [Copyright &y& Elsevier]

The hydrogen concentrations in δ-phase titanium hydrides (δ-TiHx: 1.6), prepared by means of Sieverts apparatus, have been measured by means of elastic recoil detection (ERD) and neutron radiography (NRG) methods which are non-destructive hydrogen analyses. It is concluded that the hydrogen concentration in TiHx is determined by the ERD measurement with an accuracy of ±0.05. The hydrogen concentrations in the hydrides with various H/Ti ratios have been also estimated by combining the NRG data with a general Monte Carlo neutron-particle transport code, where the neutron scattering process during the NRG measurement is simulated. [Copyright &y& Elsevier]

Abstract: A polymer electrolyte fuel cell (PEFC) consists of a membrane electrode assembly (MEA), gas diffusion layers (GDL), hydrogen and oxygen supply channels. At the anode, protons and electrons are generated, while at the cathode the protons and electrons combine to form water. The condensed water may affect the fuel cell performance. In order to clarify the effect of water distribution on the PEFC performance, three-dimensional water distribution in the PEFC was visualized by using a neutron radiography facility at JRR-3 in JAEA. For observing the detailed water distribution, a small sized PEFC was designed. Size of the gas channel is 1mm width and 0.5mm depth. Thickness of the MEA and the GDL are about 50 and 200μm. The electrode area is 0.35×3.5cm2. The PEFC was set on an automatic rotating stage, and a picture was taken every 2.25° by using a cooled CCD camera with grey scale of 16bit. The exposure time was set at 15s. Using the 80 pictures which correspond to 180°, a computed tomography (CT) was carried out. In order to observe water distribution with high spatial resolution, the LiF scintillator with a thickness of 50μm was used. From the water distributions parallel and perpendicular to the MEA, existence of water around O-ring can be confirmed. However, the detailed distribution in the PEFC is difficult to obtain from the two-dimensional pictures. On the other hand, CT pictures make possible to obtain the three-dimensional water distribution. In this study, the spatial resolution of 76.5μm was achieved, and existence of water in the PEFC could be confirmed. [Copyright &y& Elsevier]

Organic single-crystal transistors allowed the authors to investigate the essential features of short-channel devices. Rubrene single-crystal transistors with channel lengths of 500 and 100 nm exhibited good field-effect characteristics under extremely low operation voltages, although space charge limited current degrades the subthreshold properties of 100 nm devices. Furthermore, bias-stress measurements revealed the remarkable stability of organic single-crystal transistors regardless of device size. The bias-stress effect was explained by the trapping of gate-induced charges into localized density of states in the single-crystal channel. [ABSTRACT FROM AUTHOR]

This paper describes an overview of our recent discovery – clear demonstration that LiF crystals can be efficiently used as a high-performance neutron imaging detector based on optically stimulated luminescence of color centers generated by neutron irradiation. It is shown that the neutron images we have obtained are almost free from granular noise, have a spatial resolution of ${\sim}5.4~{\rm\mu}\text{m}$ and a linear response with a dynamic range of at least $10^{3}$. The high contrast and good sensitivity of LiF crystals allow us to distinguish two holes with less than 2% transmittance difference. We propose to use such detectors in areas where high spatial resolution with high image gradation resolution is needed, including diagnostics of different plasma sources such as laser and z-pinch produced plasmas. [ABSTRACT FROM AUTHOR]