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The earliest colonisation of oceanic islands by Homo sapiens occurred ~50 000–30 000 years ago in the Western Pacific, yet how this was achieved remains a matter of debate. With a focus on East Asia, the research presented here tests the hypothesis that bamboo rafts were used for these early maritime migrations. The authors review the evidence for Palaeolithic seafaring in East Asia as the context for an experimental archaeology project to build two bamboo watercraft. Sea trials demonstrate the unsuitability of bamboo, at least in East Asia, indicating that more sophisticated and durable vessels would have been required to traverse the Kuroshio Current.
It is generally accepted that oceanic plate subduction has occurred along the eastern margin of Asia since about 500 Ma ago. Therefore, the Japanese Islands have a >500 Ma history of oceanic plate subduction in their geological records. In this paper, the accretionary history of the Japanese Islands is divided into six main stages based on the mode and nature of tectonic events and the temporal gaps in the development of accretionary processes. In the first stage, oceanic plate subduction and accretion started along the margin of Gondwana. After detachment of the North and South China blocks in Devonian time, accretionary complexes developed along island arcs offshore of the South and North China blocks. After the formation of back arc basins such as the Japan Sea, accretionary processes occurred only along the limited convergent margin, e.g. Nankai Trough. Detrital zircons of sandstones revealed the accretionary history of Japan. An evaluation of a comprehensive dataset on detrital zircon populations shows that the observed temporal gaps in the development of the Japanese accretionary complexes were closely related to the intensity of igneous activity in their provenance regions. Age distributions of detrital zircons in the accretionary complexes of Japan change before and after the Middle Triassic period, when the collision of the South and North China blocks occurred.
The genus Neomonoceratina, which dominated the ostracod assemblage in the uppermost part of the Akasaki Formation (Miroku Group) of the Kyushu Island, Japan, is associated with the benthic foraminifer Ammonia cf. beccarii, mollusca Terebralia? sp. and Anomia sp., and the oogonium of Charophyceae, indicating a marine-to-brackish estuarine environment involving inflowing freshwater. This is the first record of Eocene coastal-estuarine ostracods from the eastern margin of the Eurasian continent and demonstrates that different pre-Neogene coastal-estuarine ostracod assemblages flourished in this region. The assemblages comprised five ostracod species (including one novel species) assigned to the genera Neomonoceratina, Paijeiborchella, Propontocypris and Parakrithella. These species exhibited genus-level links with the Eocene borehole cores along the continental shelf of the East China Sea and other areas of Kyushu. Fossil data of characteristic Eocene coastal-estuarine genera collected worldwide indicate that different characteristic genera inhabited each region. For example, Neomonoceratina originated on the Indian subcontinent by the Early Paleocene period at the latest, along with the northern drift of the Indian subcontinent. These species subsequently diversified west and east with the equatorial current and counter-current via the Tethys and reached the eastern margin of the Eurasian continent among the various eastwards-migrating species, where one genus ultimately adapted to the coastal-estuarine environment. Notably, the coastal-estuarine ostracod assemblage of the eastern margin of the Eurasian continent differs completely from that of the Tethys during the Eocene period. Our results suggest that coastal-estuarine ostracod assemblages are a powerful tool for palaeogeographic reconstruction.
Periodic array of metallic nanocylinder combined with the highly luminous dielectric layer is a good platform to control the intensity, spectral shape and directionality of photoluminescence (PL). In spite of its importance, the effect of cylinder height on the PL properties has not been verified experimentally. Here we investigate the effect of cylinder height on the PL properties both experimentally and numerically. The system consisted of a highly luminous layer made of Eu(III) complex and a series of periodic array of aluminum nanocylinders with different heights. The strongest directional PL was achieved when the height is similar to the diameter, i.e., the aspect ratio close to unity. Our finding is useful for designing the compact and efficient luminescence source with directional output.
In order to integrate porous dielectric materials into the next generation of Cu/low-k interconnect, the porous material has to be sealed against metal barrier precursor. We have reported pore sealants which forms ultra-thin (< 3 nm-thick) layer on top of the surface of porous low-k film while the pore sealant does not diffuse into pores. In this study, it was investigated how pore seal layer is formed on the surface of porous material and how pore mouths are sealed by pore seal layer. It was found that 1) thickness of the pore seal layer is well-controlled in the range < 5 nm, by varying spin rate and concentration of solid, 2) minimal thicknesses of the pore seal layer needed to achieve an efficient sealing for porous low-k films whose pore radius is 1.5 nm was 2.6 nm. 3) Larger pores, whose pore radius is 4.2 nm, were sealed completely with an expansion of our technology.
Accumulating evidence suggests that orally ingested lactoferrin protects against inflammation. To assess the efficacy of orally administered bovine lactoferrin (bLF) against hepatitis and to identify the underlying mechanism, in the present study, we used four mouse models of hepatitis induced by d-galactosamine (GalN), carbon tetrachloride (CCl4), GalN plus lipopolysaccharide (LPS) and zymosan plus LPS. Intraperitoneal (i.p.) injection of GalN (500 mg/kg body weight) in mice treated with bovine serum albumin (BSA) for 14 d significantly increased serum aspartate aminotransferase (AST) concentrations compared with the untreated mice. However, orally administered bLF reduced AST concentrations compared with BSA treatment. In mice that received a single injection (0·4 ml/kg) and twice-weekly injections (0·08 ml/kg) of CCl4 for 24 weeks and pretreated with bLF for 14 d and 24 weeks, respectively, significantly suppressed alanine aminotransferase and AST concentrations were observed compared with the BSA-treated control. Oral administration of bLF for 14 d before i.p. injection of LPS (5 mg/kg) plus GalN (1 g/kg) significantly improved the survival rate. In mice that received intravenous injection of zymosan (25 mg/kg) and LPS (15 μg/kg) at 7 d intervals, bLF reduced the elevation of AST concentrations and enhanced the production of IL-11 and bone morphogenetic protein 2 in the small intestine compared with the BSA-treated control. To evaluate the effects of IL-11, we used IL-11 receptor α-null mice treated with GalN, CCl4 and zymosan plus LPS. In this group, the activity of bLF was not significantly different from that of BSA. These data indicate that orally ingested bLF enhances the expression of IL-11 in the small intestine and up-regulates protective activity in mice with hepatitis.
Lattice volume expansion or amorphization renders EuTiO3 ferromagnetic, although the stable phase of crystalline EuTiO3 is an antiferromagnet. The lattice volume expansion is induced into the crystalline EuTiO3 thin film by utilizing the lattice mismatch between the thin film and a substrate. The magnetization at low temperatures monotonically increases with an increase in lattice volume for the crystalline EuTiO3 thin film, coincident with the results of calculations based on the hybrid Hartree–Fock density functional approach. The ferromagnetic interaction between Eu2+ ions is enhanced by the amorphization as well; the amorphous EuTiO3 thin film becomes a ferromagnet, and the Curie temperature is higher for amorphous Eu2TiO4 than for its crystalline counterpart. The phenomenon, that is, the volume expansion- and amophization-induced ferromagnetism, is explained in terms of the competition between ferromagnetic and antiferromagnetic interactions among Eu2+ ions.
Bulk EuTiO3 is known as a compound in which spin and soft phonon mode is strongly coupled. Recent theoretical study suggests that application of stress or formation of strain leads to a drastic change in magnetic and dielectric properties of EuTiO3 and that so-called multiferroic properties emerge under such a situation. In the present study, effect of strain induced by a substrate, on which EuTiO3 thin film is deposited, on the magnetic properties of the film has been experimentally examined. By using a pulsed laser deposition method, EuTiO3 thin film has been deposited on different kinds of substrate, i.e., LaAlO3, SrTiO3, and DyScO3; the lattice parameter of these compounds is smaller than, just the same as, and larger than that of EuTiO3, respectively. X-ray diffraction analysis confirms that the strain induced in the plane of as-deposited EuTiO3 thin films on different substrates is coincident with the lattice parameter of the substrate compounds. Also, all the as-deposited EuTiO3 thin films manifest elongation of lattice in a direction perpendicular to the film surface. Temperature dependence of magnetization indicates that all the thin films exhibit ferromagnetic behavior at low temperatures. The magnetization at 2 K under a magnetic field of 100 Oe is the highest for EuTiO3 on DyScO3 and the lowest for EuTiO3 on LaAlO3. The experimental result is coincident with the first-principles calculations which predict that ferromagnetic spin configuration becomes more stable as the lattice volume of EuTiO3is increased.
Studying a multi-dimensional structure of supernovae (SNe) gives important constraints on the mechanism of the SN explosion. Polarization measurement is one of the most powerful methods to study the explosion geometry of extragalactic SNe. Especially, Type Ib/c SNe are the ideal targets because the core of the explosion is bare. We have performed spectropolarimetric observations of Type Ib/c SNe with the Subaru telescope. We detect a rotation of the polarization angle across the line, which is seen as a loop in the Q - U plane. This indicates that axisymmetry is broken in the SN ejecta. Adding our new data to the sample of stripped-envelope SNe with high-quality spectropolarimetric data, five SNe out of six show a loop in the Q - U plane. This implies that the SN explosion commonly has a non-axisymmetric, three-dimensional geometry.
Few studies have addressed the relation between dietary patterns and colorectal cancer in Japan. We investigated dietary patterns in relation to colorectal cancer risk in a community-based case–control study. The association with dietary patterns was also examined for different sites of colorectal cancer. Data were derived from the Fukuoka Colorectal Cancer Study, including 800 cases and 775 controls interviewed from September 2000 to December 2003. The cases were admitted to one of the participating hospitals for the first surgical treatment during this period. We identified dietary patterns using principal component analysis of intakes of twenty-nine items of food groups and specific foods. Quartile categories of each dietary pattern were used, and non-dietary lifestyle factors and total energy intake were adjusted for in the analysis. We identified three dietary patterns: prudent, high-fat and light-meal patterns. The prudent dietary pattern characterised by high intakes of vegetables, fruits, seafoods and soya foods showed a nearly significant protective association with the overall risk of colorectal cancer (trend P = 0·054), and it was statistically significantly related to a decreased risk of distal colon cancer (trend P = 0·002), but not to that of either proximal colon or rectal cancer. The high-fat and light-meal dietary patterns were not materially related to the overall or site-specific risk of colorectal cancer. In summary, a prudent dietary pattern was associated with a decreased risk of colorectal cancer, especially with that of distal colon cancer, in a fairly large case–control study in Japan.
Compound formation properties of very finely layered Mg/Al laminate composite (“super laminate composite”) were investigated. Almost uniform Mg17Al12 compound was obtained by heat treatment of the super laminate at 673K in less than 0.6ks(10 minutes). The rate control process of the compound formation is thought to be the diffusion of Mg in Al. Hydrogenation properties of thus obtained Mg17Al12 compound were also studied and its absorption capacity and dissociation pressure were almost the same as those previously reported material, which was prepared by a longer time heat treatment.
Mg has 7.6 mass% of high gravimetric hydrogen density, an abundance of resources and inexpensive price compared with other functional materials. Owing to these merits, it has been the major subject of hydrogen storage study. However, it is unsuitable for practical application due to thermodynamic stability and slow kinetics of Mg hydride. Therefore, many ways such as fabrication of nanocrystalline or addition of catalyst have been proposed to solve the problems of Mg hydride system. Copper and aluminum are inexpensive and can obtain easily as well as Mg. Each eutectic alloy could be produced by sintering process and observed improvement of reaction with hydrogen. Mg2Cu laminate, one phase of Mg-Cu eutectic alloy, could also be produced by cold-rolling process, and it showed reversible reaction with hydrogen, at this study.
Pure and Al2O3(2%, 5%, 8%) doped sintered ZnO (n-type) and pure sintered Ca3Co4O9 (p-type) pellets were prepared by conventional solid state synthesis starting from the oxides. The sintered pellets were cut by a diamond saw in a pillar shape (15 mm×5 mm×5 mm) for experimental checks. The best doped sample was 2 % Al2O3 ZnO showing Seebeck coefficient S = -180 mV/K and electrical conductivity σ = 8 S/cm at 400°C, while thermal conductivity κ = 1.8 W/m×K at 600°C. Typical values for Ca3Co4O9 were S = 82.5 mV/K and σ = 125 S/cm at 800°C, while κ = 1.01 W/m×K at 600°C.
Several modules fabricated by elements cut from sintered pellets were tested and the best performance was obtained in the module formed by six 2 % Al2O3ZnO/ Ca3Co4O9 couples, that generated an output power P = 300 mV at 500°C (when ΔT = 260°C).
We have prepared Mg/Pd laminate composites with (Mg/Pd)=6, 3 and 2.5 atom ratios, by a super lamination technique. The homogeneous Mg-Pd intermetallic compounds, Mg6Pd, Mg3Pd and Mg5Pd2, are formed during the initial activation process. We investigated the hydrogen storage properties of these materials. The compounds can reversibly absorb and desorb a large amount of hydrogen, up to 1.46˜0.9 H/M, at 573 K. Except for the Mg5Pd2-hydrogen system, the pressure composition-isotherms show two plateaux. The mechanism of the phase transition during hydrogenation/dehydrogenation was analyzed by in-situ XRD measurements. These intermetallic compounds absorb and desorb hydrogen through reversible multistage disproportionation and recombination processes.
We report the preparation and thermoelectric properties of oriented higher manganese silicide (HMS) with a composition of MnSi1.73 bulk. The grain alignment and densification were achieved by rotating high magnetic field and spark plasma sintering (SPS) techniques, respectively. The easy magnetization axis of MnSi1.73 was found to be c-axis, and the applied magnetic field of 2 T was strong enough to rotate the powder with a mean grain size of 1 μm. The c-axis of grains was oriented when applying the magnetic field, and the degree of orientation was further increased after heat treatment. However, a secondary phase that was mono manganese silicide (MnSi) was observed as a result of oxidation on the surface of synthesized powder. The electrical conductivity of the c-axis oriented specimen along the ab-plane was about 40% larger than that for sample processed only by SPS, while the Seebeck coefficient of oriented and nonoriented specimens showed similar values regardless of existence of the second phase. Consequently, the power factor of the c-axis oriented specimen along the ab-plane was enhanced by about 35% compared to the nonoriented one. The proposed approach is found to be very effective not only in obtaining the oriented materials with nonductility but also in enhancing the thermoelectricity.
The Au nano-particles are deposited on the metal oxide substrate, TiO2 and CeO2, and the structure of the Au particles and Au-metal oxide interface was observed by TEM and HAADF-STEM. It was found that the growth of Au particles on TiO2 and CeO2 by heating treatment is suppressed in the reductive atmosphere. The HAADF-STEM observation was carried out and the atomically resolved HAADF-STEM images in profile-view are successfully obtained for Au/TiO2 and Au/CeO2 samples. The Au particles tend to supported on CeO2 surface with the flat interface compared to the TiO2 substrate. The incoherent interface is observed for the Au particles-CeO2 interface.
Microstructures and hydrogen storage properties of Mg/Cu super-laminates were compared to clarify the effect of initial activation. The initial activation change micro/nano-structures of Mg/Cu super-laminates into Mg2Cu with layered structure in fine grain size of about 1μm and pores highly dispersed between layers in sub-micrometer size. Large surface area, dense defects and short diffusion distance for the reaction enable Mg/Cu super-laminates to absorb hydrogen very quickly.
A small p-n diode array was fabricated on a polycrystalline Si substrate and the electrical characteristics were measured for each small diode to evaluate the distribution of energy conversion efficiency in the substrate. The crystal qualities in conjunction with the electrical characteristics were also evaluated. We found large variations in measuring the current-voltage (I-V) characteristics of the p-n diode. We also observed variations in quality even in diodes without any grain boundaries at the p-n junction. Therefore, we evaluated crystalline quality using various techniques to compare the diode characteristics. We found clear evidence in photo-luminescence (PL) mapping, where grains, including degraded diodes, were darker in the mapping, implying lower PL intensities than the others. The PL spectra obtained from the “dark grains” included D-lines indicating the existence of dislocations. We could conclude that the electrical characteristics of p-n diodes were not only affected by grain boundaries but also by crystalline defects evaluation such as dislocations. We observed a Secco-etched surface for crystalline defects evaluation using an optical microscope. The origins of etch pits were also determined by transmission electron microscope (TEM) and three different types of defects were confirmed.
Super-laminates have been attracting attention since co-authors Ueda et al. reported that Mg/Cu super-laminates showed reversible hydrogenation and dehydrogenation at 473K. The Mg/Cu super-laminates were prepared by a repetitive fold and roll method. Initial activation at 573 K led the super-laminates to absorb hydrogen at 473K. TEM observations of micro/nano-structures in the super-laminates were performed in order to clarify the process of hydrogenation and dehydrogenation at 473K, The as-rolled Mg/Cu super-laminates have laminated structures in size of sub-micrometer thickness composed of Mg and Cu layers with dense lattice defects. The super-laminates after initial activation keep laminated structure and have uniformly distributed pores with a sub-micrometer diameter. It is considered that these micro/nano-structures of Mg/Cu super-laminates lead to lower dehydrogenation temperature and better kinetics, which would contribute to achieve high performance hydrogen storage materials.