107 research outputs found
General Rule and Materials Design of Negative Effective U System for High-T_c Superconductivity
Based on the microscopic mechanisms of (1) charge-excitation-induced negative
effective U in s^1 or d^9 electronic configurations, and (2)
exchange-correlation-induced negative effective U in d^4 or d^6 electronic
configurations, we propose a general rule and materials design of negative
effective U system in itinerant (ionic and metallic) system for the realization
of high-T_c superconductors. We design a T_c-enhancing layer (or clusters) of
charge-excitation-induced negative effective connecting the superconducting
layers for the realistic systems.Comment: 11 pages, 1 figures, 2 tables, APEX in printin
Prediction of Intrinsic Defects in Hydrogenated Amorphous Silicon by ab initio Molecular Dynamics
Intrinsic defects in hydrogenated amorphous silicon (a-Si : H) are investigated using ab initio molecular-dynamics simulation. It is predicted that the hydrogen-passivated dangling bond (Si-H), the positively-ionized Si-H-Si three-centered bond (Si-H^+-Si), the negatively-ionized three-fold-coordinated dangling-bond (D^-), and the five-fold-coordinated floating-bond (F_5) are the intrinsic defects in a-Si : H. We discuss the role of intrinsic defects and hydrogen related to the origin of the photo-induced defect in a-Si : H based upon the simulation
An Al-doped SrTiO3 photocatalyst maintaining sunlight-driven overall water splitting activity for over 1000 h of constant illumination
Photocatalytic water splitting is a viable approach to the large-scale production of renewable solar hydrogen. The apparent quantum yield for this reaction has been improved, but the lifespan of photocatalysts functioning under sunlight at ambient pressure have rarely been examined, despite the critical importance of this factor in practical applications. Herein, we show that Al-doped SrTiO3 (SrTiO3: Al) loaded with a RhCrOx (rhodium chromium oxide) cocatalyst splits water with an apparent quantum yield greater than 50% at 365 nm. Moreover, following the photodeposition of CoOOH and TiO2, this material maintains 80% of its initial activity and a solar-to-hydrogen energy conversion efficiency greater than or equal to 0.3% over a span of 1300 h under constant illumination by simulated sunlight at ambient pressure. This result is attributed to reduced dissolution of Cr in the cocatalyst following the oxidative photodeposition of CoOOH. The photodeposition of TiO2 further improves the durability of this photocatalyst. This work demonstrates a concept that could allow the design of longterm, large-scale photocatalyst systems for practical sunlight-driven water splitting.ArticleCHEMICAL SCIENCE.10(11):3196-3201(2019)journal articl
The MAXI Mission on the ISS: Science and Instruments for Monitoring All Sky X-Ray Images
The MAXI (Monitor of All-sky X-ray Image) mission is the first astronomical
payload to be installed on the Japanese Experiment Module-Exposed Facility
(JEM-EF) on the ISS. It is scheduled for launch in the middle of 2009 to
monitor all-sky X-ray objects on every ISS orbit. MAXI will be more powerful
than any previous X-ray All Sky Monitor (ASM) payloads, being able to monitor
hundreds of AGN. MAXI will provide all sky images of X-ray sources of about 20
mCrab in the energy band of 2-30 keV from observation on one ISS orbit (90
min), about 4.5 mCrab for one day, and about 1 mCrab for one month. A final
detectability of MAXI could be 0.2 mCrab for 2 year observations.Comment: 12 pages, 11 figures, accepted for publication in Publications of the
Astronomical Society of Japa
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