The UV/Optical Telescope (UVOT) is one of three instruments flying aboard the Swift Gamma-ray Observatory. It is designed to capture the early (~1 minute) UV and optical photons from the afterglow of gamma-ray bursts in the 170-600 nm band as well as long term observations of these afterglows. This is accomplished through the use of UV and optical broadband filters and grisms. The UVOT has a modified Ritchey-Chrétien design with micro-channel plate intensified charged-coupled device detectors that record the arrival time of individual photons and provide subarcsecond positioning of sources. We discuss some of the science to be pursued by the UVOT and the overall design of the instrument.
Abstract. The XMM-OM instrument extends the spectral coverage of the XMM-Newton observatory into the ultraviolet and optical range. It provides imaging and time-resolved data on targets simultaneously with observations in the EPIC and RGS. It also has the ability to track stars in its field of view, thus providing an improved post-facto aspect solution for the spacecraft. An overview of the XMM-OM and its operation is given, together with current information on the performance of the instrument.
We have synthesized the novel composite membranes composed of sulfonated polyimide nanofibers and sulfonated polyimide for proton exchange membrane fuel cell. It was clear that the polyimides within nanofiber were significantly oriented or aggregated when electrospun; as the result, the membrane stability, such as oxidative and hydrolytic stabilities, of the composite membrane was significantly improved with an increase in nanofiber, and oxygen permeability of the composite membrane also decreased when compared to that determined in the membrane without nanofibers. In addition, the proton conductivity of the membrane in the parallel direction indicated a significantly higher value when compared to that determined for the membrane in the perpendicular direction or for the membrane without nanofibers prepared with conventional solvent-casting method. Consequently, nanofibers proved to be promising materials as a proton exchange membrane and the composite membrane containing nanofibers may have potential application for use in fuel cells.
Large amounts of water to cool the fuel rods was supplied and this procedure increased the amount of water contaminated with radionuclides, and the contaminated water leaked onto the land and into the ocean. By early April (end of May), the estimated total amount of accidentally and deliberately emitted 137 Cs was 2.6 (3.5 ± 0.7) PBq (Tsumune et al., 2011). The maximum 137 Cs concentrations at the north drain outlet of the plant and at 30 km off Fukushima were 68,000 Bq L-1 (on 30 March: TEPCO, 2011a) and 186 Bq L-1 (on 15 April: MEXT, 2011), respectively. Thereafter, these concentrations have been decreasing, but the level of radioactivity in seawater is still higher than the background level due to the atmospheric nuclear weapons test before 11 March (MOE, 2009). Moreover, about 0.11 million tons of radioactivity-contaminated water (total radioactivity, 720 PBq, including 137 Cs, 140 PBq) had
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