501 research outputs found

    Implementation of voyage data recording device using a digital forensics-based hash algorithm

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    Identifying the causes of marine accidents is difficult because of problems in scene preservation, reenactment, and procuring of witnesses. Thanks to new regulations, larger vessels are now required to carry voyage data recorders (VDRs) and automatic identification systems (AISs). However, the content of these devices, which is created, stored, and managed digitally, has security vulnerabilities such as the potential for data modification. Therefore, when managing digital records it is important to guarantee reliability. To this end, we suggest a digital forensics-based digital records migration method using a hash algorithm to guarantee the integrity and authenticity of digital records

    Physical properties of transparent perovskite oxides (Ba,La)SnO3 with high electrical mobility at room temperature

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    Transparent electronic materials are increasingly in demand for a variety of optoelectronic applications. BaSnO3 is a semiconducting oxide with a large band gap of more than 3.1 eV. Recently, we discovered that La doped BaSnO3 exhibits unusually high electrical mobility of 320 cm^2(Vs)^-1 at room temperature and superior thermal stability at high temperatures [H. J. Kim et al. Appl. Phys. Express. 5, 061102 (2012)]. Following that work, we report various physical properties of (Ba,La)SnO3 single crystals and films including temperature-dependent transport and phonon properties, optical properties and first-principles calculations. We find that almost doping-independent mobility of 200-300 cm^2(Vs)^-1 is realized in the single crystals in a broad doping range from 1.0x10^19 to 4.0x10^20 cm^-3. Moreover, the conductivity of ~10^4 ohm^-1cm^-1 reached at the latter carrier density is comparable to the highest value. We attribute the high mobility to several physical properties of (Ba,La)SnO3: a small effective mass coming from the ideal Sn-O-Sn bonding, small disorder effects due to the doping away from the SnO2 conduction channel, and reduced carrier scattering due to the high dielectric constant. The observation of a reduced mobility of ~70 cm^2(Vs)^-1 in the film is mainly attributed to additional carrier-scatterings which are presumably created by the lattice mismatch between the substrate SrTiO3 and (Ba,La)SnO3. The main optical gap of (Ba,La)SnO3 single crystals remained at about 3.33 eV and the in-gap states only slightly increased, thus maintaining optical transparency in the visible region. Based on these, we suggest that the doped BaSnO3 system holds great potential for realizing all perovskite-based, transparent high-frequency high-power functional devices as well as highly mobile two-dimensional electron gas via interface control of heterostructured films.Comment: 31 pages, 7 figure

    A highly active and redox stable novel ceramic anode with in-situ exsolution of nanocatalysts

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    Layered perovskite novel ceramic anode (referred to as SGNM) phases were evaluated for use in solid oxide fuel cells (SOFCs). Hydrogen temperature programmed reduction (H2-TPR) analysis of the SGNM materials revealed that significant exsolution of Ni nanoparticles occurred. Consistently, the SGNM on the LSGM electrolyte showed low electrode polarization resistance in H2 at 800 °C. Moreover, after 10 redox cycles at 750 °C, the electrode area specific resistance of the SGNM anode in H2 slightly increased during cycle, indicating excellent redox stability in both reducing and oxidizing atmospheres. An LSGM-electrolyte supported SOFC employing an SGNM-based anode yielded a high power density of ~1 W cm-2 at 800 °C, which is the best performance among the any SOFCs with Ruddlesden-Popper based ceramic anodes to date. After performance measurement, we observed that metallic Ni nanoparticles (~ 25 nm) were grown in situ and homogeneously distributed on the SGNM anode surface. These exsolved nanocatalysts are believed to significantly enhance the hydrogen oxidation activity of the SGNM material. These results demonstrate that the novel SGNM material is promising as a high catalytically active and redox-stable anode for SOFCs.. Please click Additional Files below to see the full abstract

    Treatment for the Lumbosacral Soft Tissue Defect after Spine Surgery

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    The lumbosacral area is one of the most frequently operated spine regions because of the prevalence of disease in that area. Although a lumbosacral soft tissue defect after surgery due to inflammation and other causes is rare, such soft tissue defects are difficult to treat. Therefore, suitable methods for treating lumbosacral soft tissue defects are necessary. Therefore, this study introduces a case-treated with a transverse lumbosacral rotational flap

    Removal of Pb(II) from aqueous solution by a zeolite–nanoscale zero-valent iron composite

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    The effectiveness of nanoscale zero-valent iron (nZVI) to remove heavy metals from water is reduced by its low durability, poor mechanical strength, and tendency to form aggregates. A composite of zeolite and nanoscale zero-valent iron (Z–nZVI) overcomes these problems and shows good potential to remove Pb from water. FTIR spectra support nZVI loading onto the zeolite and reduced Fe0 oxidation in the Z–nZVI composite. Scanning electron micrographs show aggregation was eliminated and transmission electron micrographs show well-dispersed nZVI in chain-like structures within the zeolite matrix. The mean surface area of the composite was 80.37 m2/g, much greater than zeolite (1.03 m2/g) or nZVI (12.25 m2/g) alone, as determined by BET-N2 measurement. More than 96% of the Pb(II) was removed from 100 mL of solution containing 100 mg Pb(II)/L within 140 min of mixing with 0.1 g Z–nZVI. Tests with solution containing 1000 mg Pb(II)/L suggested that the capacity of the Z–nZVI is about 806 mg Pb(II)/g. Energy-dispersive X-ray spectroscopy showed the presence of Fe in the composite; X-ray diffraction confirmed formation and immobilization of Fe0 and subsequent sorption and reduction of some of the Pb(II) to Pb0. The low quantity of Pb(II) recovered in water-soluble and Ca(NO3)2-extractable fractions indicate low bioavailability of the Pb(II) removed by the composite. Results support the potential use of the Z–nZVI composite in permeable reactive barriers

    Removal of Pb(II) from aqueous solution by a zeolite–nanoscale zero-valent iron composite

    Get PDF
    The effectiveness of nanoscale zero-valent iron (nZVI) to remove heavy metals from water is reduced by its low durability, poor mechanical strength, and tendency to form aggregates. A composite of zeolite and nanoscale zero-valent iron (Z–nZVI) overcomes these problems and shows good potential to remove Pb from water. FTIR spectra support nZVI loading onto the zeolite and reduced Fe0 oxidation in the Z–nZVI composite. Scanning electron micrographs show aggregation was eliminated and transmission electron micrographs show well-dispersed nZVI in chain-like structures within the zeolite matrix. The mean surface area of the composite was 80.37 m2/g, much greater than zeolite (1.03 m2/g) or nZVI (12.25 m2/g) alone, as determined by BET-N2 measurement. More than 96% of the Pb(II) was removed from 100 mL of solution containing 100 mg Pb(II)/L within 140 min of mixing with 0.1 g Z–nZVI. Tests with solution containing 1000 mg Pb(II)/L suggested that the capacity of the Z–nZVI is about 806 mg Pb(II)/g. Energy-dispersive X-ray spectroscopy showed the presence of Fe in the composite; X-ray diffraction confirmed formation and immobilization of Fe0 and subsequent sorption and reduction of some of the Pb(II) to Pb0. The low quantity of Pb(II) recovered in water-soluble and Ca(NO3)2-extractable fractions indicate low bioavailability of the Pb(II) removed by the composite. Results support the potential use of the Z–nZVI composite in permeable reactive barriers

    High Mobility in a Stable Transparent Perovskite Oxide

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    We discovered that La-doped BaSnO3 with the perovskite structure has an unprecedentedly high mobility at room temperature while retaining its optical transparency. In single crystals, the mobility reached 320 cm^2(Vs)^-1 at a doping level of 8x10^19 cm^-3, constituting the highest value among wide-band-gap semiconductors. In epitaxial films, the maximum mobility was 70 cm^2(Vs)^-1 at a doping level of 4.4x10^20 cm^-3. We also show that resistance of (Ba,La)SnO3 changes little even after a thermal cycle to 530 Deg. C in air, pointing to an unusual stability of oxygen atoms and great potential for realizing transparent high-frequency, high-power functional devices.Comment: 15 pages, 3 figure
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