Electrostatic Discharge Ground Test of a Polar Orbit Satellite Solar Panel

The Advanced Land Observing Satellite that was launched by the Japan Aerospace Exploration Agency in 2006 carries a large solar-array paddle of 22 times 3 m in polar orbit. The wake side of the solar paddle can be charged to a negative value exceeding -1000 V. Numerical simulations and laboratory experiments are carried out to investigate charging and arcing phenomena on the backside of the solar paddle that has exposed bypass diode boards and silver-Teflon thermal film. Possibility of secondary arc and surge voltage between hot and return ends of power circuit has been investigated. The authors irradiate solar-panel coupons with an electron beam to simulate charging situation near the North Pole. Surface flashover is observed once the insulator potential exceeds -7000 V. The authors have also tested charging situation near the South Pole where carbon fiber-reinforced plastics surface facing dense ionospheric plasma may arc easily once a satellite potential drops to -80 or -90 V. The solar-paddle design has been modified to increase the safety margin against arcing, and tests have been carried out to identify the strength limit under extremely harsh test environment

Nuclear localization of beta-catenin involved in precancerous change in oral leukoplakia

<p>Abstract</p> <p>Background</p> <p>Oral leukoplakia is a precancerous change developed in the oral mucosa, and the mechanism that oral leukoplakia becomes malignant through atypical epithelium is not known. Here we compared the β-catenin expression detected by immunohistochemical staining in the normal oral epithelium and in the oral leukoplakia with or without dysplasia.</p> <p>Results</p> <p>The normal oral epithelium showed β-catenin expression only in the cell membrane, but not in the nuclei. In the oral leukoplakia without dysplasia, 7 out of 17 samples (41%) showed β-catenin expression in the cell membrane, and 5 samples (29%) showed expression in the nuclei. In the oral leukoplakia with dysplasia, nuclear expression of β-catenin was shown in 11 out of 12 samples (92%). Incidence of nuclear β-catenin expression was significantly different between dysplasia and normal oral epithelium (P < 0.01), and also between oral leukoplakia with dysplasia and those without dysplasia (P < 0.01). Wnt3 expression was detected in the epithelial cell membrane or cytoplasm in oral leukoplakia where nuclear expression of β-catenin was evident, but not in epithelial cells without nuclear expression of β-catenin.</p> <p>Conclusion</p> <p>The components of canonical Wnt pathway, such as Wnt3, β-catenin, and cyclin D1, were detected, implying that this pathway is potentially involved in the progression of dysplasia in oral leukoplakia.</p

Degradation of High Voltage Solar Array due to Arcing in LEO plasma Environment

A degradation test for a solar array coupon against electrostatic discharge was performed under a simulated low-Earth-orbit environment as part of research project to develop the next-generation 400-V high-voltage solar array technology. All tests were performed in a vacuum chamber with a plasma source. An inductance–capacitance–resistance circuit was used to simulate the arc current that would flow by collecting electric charge stored on cover glasses. Arcs were repeated until the solar array coupon showed degradation of electrical output. The locations, current waveform, and voltage waveforms of all the arcs during the tests were recorded. The electrical output of the coupon was measured without opening the vacuum chamber. The arc that damaged a solar cell was identified; the cell was damaged by only one arc, which occurred at the edge of the cell

CBP/p300 is a cell type-specific modulator of CLOCK/BMAL1-mediated transcription

<p>Abstract</p> <p>Background</p> <p>Previous studies have demonstrated tissue-specific regulation of the rhythm of circadian transcription, suggesting that transcription factor complex CLOCK/BMAL1, essential for maintaining circadian rhythm, regulates transcription in a tissue-specific manner. To further elucidate the mechanism of the cell type-specific regulation of transcription by CLOCK/BMAL1 at the molecular level, we investigated roles of CBP/p300 and tissue-specific cofactors in CLOCK/BMAL1-mediated transcription.</p> <p>Results</p> <p>As shown previously, CBP/p300 stimulates CLOCK/BMAL1-mediated transcription in COS-1 cells. However, CBP/p300 repressed CLOCK/BMAL1-mediated transcription in NIH3T3 cells and knockdown of CBP or p300 expression by siRNA enhanced this transcription. Studies using GAL4-fusion proteins suggested that CBP represses CLOCK/BMAL1-mediated transcription by targeting CLOCK. We further investigated mechanisms of this cell type-specific modulation of CLOCK/BMAL1-mediated transcription by CBP by examining roles of co-repressor HDAC3 and co-activator pCAF, which are highly expressed in NIH3T3 and COS cells, respectively. CBP repressed CLOCK/BMAL1-mediated transcription in COS-1 cells when HDAC3 was overexpressed, but activated it in NIH3T3 cells when pCAF was overexpressed. CBP forms a complex with CLOCK by interacting with HDAC3 or pCAF; however, direct interaction of CBP with CLOCK was not observed.</p> <p>Conclusion</p> <p>Our findings indicate possible mechanisms by which CBP/p300 tissue-specifically acts cooperatively with pCAF and HDAC3 either as a co-activator or co-repressor, respectively, for CLOCK/BMAL1.</p

Pulmonary intravascular large B-cell lymphoma successfully treated with rituximab, cyclophosphamide, vincristine, doxorubicin and prednisolone immunochemotherapy: Report of a patient surviving for over 1 year

A 73-year-old man with a history of lethargy, fever and dyspnea was admitted to Tottori University Hospital. A computed tomography (CT) scan revealed splenomegaly and diffusely spreading ground‑glass opacities (GGOs) in both lungs. A video‑assisted thoracoscopic surgery (VATS)‑guided lung biopsy revealed intravascular proliferation of large atypical lymphoid cells in the arteries, veins and alveolar walls. The patient was diagnosed with intravascular large B‑cell lymphoma (IVLBCL); he received 6 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R‑CHOP) immunochemotherapy and has remained in complete remission for >1 year. Although IVLBCL is a rare disease, it should be considered in the differential diagnosis of pulmonary diffuse lesions that present with GGOs on CT scans

Development of 400V Solar Array Technology for Low Earth Orbit Plasma Environment

To realize a 400 V operation in low Earth orbit (LEO), problems of arcing caused by interaction between spacecraft and surrounding LEO plasma must be overcome. This paper is a summary report of the laboratory tests carried out to develop a 400 V solar array technology. Among various designs tested, a design of covering a solar array surface with transparent film, called film coupon, was the most promising mitigation method to prevent arc inception. The authors carried out various tests on the film coupons considering a realistic situation encountered in orbit. The coupon biased to -400 V in LEO-like plasma had no arc for more than 25 h. Other tests involved UV exposure, atomic-oxygen exposure, thermal cycling, and debris impact. Conductive substrate made of carbon fiber reinforced plastic suffered many arcs at -400 V. Sustained arc between a solar cell and the substrate was also observed upon a simulated debris impact. Therefore, the use of flexible substrate is adequate for 400 V solar array in LEO environment. To avoid the snapover effect near the positive end of the array circuit, only the negative part of the array circuit exceeding the arc-inception threshold should be covered by film, or an electron collector should be deploye