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Transition metal dichalcogenides are 2D structures with remarkable electronic, chemical, optical and mechanical properties. Monolayer and crystal properties of these structures have been extensively investigated, but a detailed understanding of the properties of their few-layer structures are still missing. In this work we investigated the mechanical differences between monolayer and multilayer WSe2 and MoSe2, through fully atomistic molecular dynamics simulations (MD). It was observed that single layer WSe2/MoSe2 deposited on silicon substrates have larger friction coefficients than 2, 3 and 4 layered structures. For all considered cases it is always easier to peel off and/or to fracture MoSe2 structures. These results suggest that the interactions between first layer and substrate are stronger than interlayer interactions themselves. Similar findings have been reported for other nanomaterials and it has been speculated whether this is a universal-like behavior for 2D layered materials. We have also analyzed fracture patterns. Our results show that fracture is chirality dependent with crack propagation preferentially perpendicular to W(Mo)-Se bonds and faster for zig-zag-like defects.
We have made a CO(J=2-1) observations using the Nobeyama 45m telescope aimed at examining the physical properties of the molecular gas in this object. The upper limit obtained is 1.8 mK (3σ) at a velocity resolution of 100 km s−1, which leads to an upper limit on the molecular gas mass of 5.3 × 1011M⊙, if we assume a line width of 250 km s−1 obtained in the CO(J = 5 - 4) line (rest-frame) and the Galactic CO-to-H2 conversion factor of 4.5 (M⊙ K km s−1 pc2). The line ratio between the 2–1 line and the 5–4 line as well as those from the 7–6 and the 4–3 lines (Omont et al. 1996, Nature, 382, 428) imply that the mean gas density is as high as 103–5 cm−3, which is comparable to that in nearby star burst galaxies (e.g., Solomon et al. 1992, ApJ, 387, L55).
We have made a CO (J=2−1) observation using the Nobeyama 45m telescope aimed at examining physical properties of the molecular gas in the object. Upper limit obtained is 1.8 mK (3σ) at a velocity resolution of 100 km s−1, which leads to an upper limit on the molecular gas mass of 5.3 × 1011M⊙, if we assume a line width of 250 km s−1 obtained in J = 5–4 line and the Galactic CO-to-H2 conversion factor of 4.5 M⊙ K km s−1 pc2. The line ratio between 2–1 line and 5–4 line as well as those from 7–6 and 4–3 lines (Omont et al. 1996) imply that the mean gas density is as high as 103–5 cm−3, which is comparable to that in nearby star burst galaxies (e.g., Solomon et al. 1992).
Since the bulk of the energy density of the Cosmic X-ray Background (CXB) resides in the harder energy band than that of the ROSAT band (0.5-2 keV) and since the X-ray sources identified in the ROSAT band have X-ray spectra softer than that of the CXB, investigation of nature of the X-ray sources at the harder energy band is indispensable to solve the origin of the CXB. However, only 2-3% of the CXB in the hard band (2-10 keV) had been resolved into discrete sources (Piccinotti et al. 1982, ApJ 253, 485). We present our preliminary results of optical follow-up observations of the ASCA Lynx deep survey.
We report the results of near-infrared observations of a type-2 QSO, AX J08494+4454 at z = 0.9 which was identified in our optical follow-up observations of the ASCA Lynx deep survey. This object has a hard X-ray spectrum with an X-ray luminosity of about 1×1044 erg s−1 in 2–10 keV. The optical spectrum shows high-excitation and high-ionization lines but no significant broad Hβ emission. These properties strongly suggest that this object is a “type-2” QSO (Ohta et al. 1996).
We have conducted 1.1 mm ALMA observations of a contiguous 105” × 50” or 1.5 arcmin2 window in the SXDF-UDS-CANDELS. We achieved a 5σ sensitivity of 0.28 mJy, giving a flat sensus of dusty star-forming galaxies with LIR ~6×1011L⊙ (if Tdust=40K) up to z ~ 10 thanks to the negative K-correction at this wavelength. We detected 5 brightest sources (S/N>6) and 18 low-significant sources (5>S/N>4; they may contain spurious detections, though). One of the 5 brightest ALMA sources (S1.1mm = 0.84 ± 0.09 mJy) is extremely faint in the WFC3 and VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey uncovers a faint dust-obscured population invisible in the deep optical/near-infrared surveys. We find a possible [CII]-line emitter at z=5.955 or a low-z CO emitting galaxy within the field, allowing us to constrain the [CII] and/or CO luminosity functions across the history of the universe.
Corynebacterium ulcerans (toxigenic C. ulcerans) produces the diphtheria toxin, which causes pharyngeal and cutaneous diphtheria-like disease in people, and this bacterium is commonly detected in dogs and cats that are reared at home. It is considered dangerous when a carrier animal becomes the source of infection in people. To investigate the carrier situation of toxigenic C. ulcerans of cats bred in Japan, bacteria were isolated from 37 cats with a primary complaint of rhinitis in 16 veterinary hospitals in Osaka. Toxigenic C. ulcerans was detected in two of the cats. By drug sensitivity testing, the detected bacterium was sensitive to all investigated drugs, except clindamycin. It appears necessary to create awareness regarding toxigenic C. ulcerans infection in pet owners because this bacterium is believed to be the causative organism for rhinitis in cats.
Cicatricial pemphigoid can affect all mucosa of the upper aerodigestive tract; however, hypopharyngeal involvement is less frequent.
This paper presents a 69-year-old male diagnosed as having cicatricial pemphigoid who was experiencing difficulty swallowing. Videofluorography with barium swallow demonstrated narrow flow through the medial hypopharynx, but not through the lateral hypopharynx. Direct laryngoscopy revealed that the postcricoid hypopharyngeal lumen had become narrow due to circumferential scar formation. Interestingly, detached thin membranous webs were observed beyond the circumferential scar.
This report describes important videofluorographic and direct laryngoscopic findings showing rare hypopharyngeal involvement in a case of cicatricial pemphigoid.
More than 50% of the global population already lives in urban settlements and urban areas are projected to absorb almost all the global population growth to 2050, amounting to some additional three billion people. Over the next decades the increase in rural population in many developing countries will be overshadowed by population flows to cities. Rural populations globally are expected to peak at a level of 3.5 billion people by around 2020 and decline thereafter, albeit with heterogeneous regional trends. This adds urgency in addressing rural energy access, but our common future will be predominantly urban. Most of urban growth will continue to occur in small-to medium-sized urban centers. Growth in these smaller cities poses serious policy challenges, especially in the developing world. In small cities, data and information to guide policy are largely absent, local resources to tackle development challenges are limited, and governance and institutional capacities are weak, requiring serious efforts in capacity building, novel applications of remote sensing, information, and decision support techniques, and new institutional partnerships. While ‘megacities’ with more than 10 million inhabitants have distinctive challenges, their contribution to global urban growth will remain comparatively small.
Energy-wise, the world is already predominantly urban. This assessment estimates that between 60–80% of final energy use globally is urban, with a central estimate of 75%. Applying national energy (or GHG inventory) reporting formats to the urban scale and to urban administrative boundaries is often referred to as a ‘production’ accounting approach and underlies the above GEA estimate.
We present the results of the Nobeyama Radio Observatory (NRO) M 33 All Disk (30′ × 30′,
or 7.3 kpc × 7.3 kpc) Survey of Giant Molecular Clouds (NRO MAGiC) based on
12CO(J = 1–0) observations using the NRO 45-m telescope and
12CO(J = 3–2) observations using the ASTE 10-m telescope.
The spatial resolution of the resultant 12CO(J = 1–0) map is
193, corresponding to 81 pc, which is sufficient to identify each Giant Molecular Cloud
(GMC) in the disk. We found clumpy structures with a typical spatial scale of
~100 pc, corresponding to GMCs, and no diffuse, smoothly distributed component
of molecular gas at this sensitivity.
We obtained a map of the molecular fraction,
fmol = ΣH2/(ΣHi + ΣH2),
at a 100-pc resolution. This is the first fmol map covering an
entire galaxy with a GMC-scale resolution. The correlation between
fmol and gas surface density shows two distinct sequences.
The presence of two correlation sequences can be explained by differences in metallicity,
i.e., higher (~2-fold) metallicity in the central region
(r < 1.5 kpc) than in the outer parts. Alternatively,
differences in scale height can also account for the two sequences, i.e.,
increased scale height toward the outer disk.
Optical properties of fully-strained wurtzite and zincblende InxGa1-xN/GaN multiple quantum well (MQW) structures were compared to discuss the origin of exciton localization. In contrast to the hexagonal InGaN MQWs, the photoluminescence (PL) peak energy of cubic InGaN MQWs showed a moderate blueshift with decreasing well thickness, L, and low-temperature PL decay time of the cubic MQWs did not depend strongly on L. The results imply that the wavefunction overlap in cubic InGaN MQWs was not reduced compared to the hexagonal ones, since they do not suffer from the electric field normal to the QW plane due either to spontaneous or piezoelectric polarization. Both MQWs exhibited a large and composition-dependent bandgap bowing, and time-resolved PL (TR-PL) signals showed a stretched-exponential decay even at room temperature. The exciton localization is considered to be an intrinsic property of InGaN.
CoFe2O4/α-Fe2O3 (ferrimagnetic / antiferromagnetic) bilayered films were prepared on α-Al2O3(102) single-crystalline substrates by helicon plasma sputtering. A well-crystallized epitaxial α-Fe2O3(102) layer was formed on the substrate, while CoFe2O4 grown on α-Fe2O3(102) was a polycrystalline layer with a (100)-preferred orientation. The α-Fe2O3(102) films without CoFe2O4 layers clearly showed a spin-flip transition at about 400 K. The spins aligned perpendicular to the film plane at room temperature changed their direction within the film plane above 400 K. However the α-Fe2O3 base layers of CoFe2O4/α-Fe2O3 bilayered films did not show any spin-flip transition. The CoFe2O4 layer on α-Fe2O3 had a large in-plane magnetic anisotropy, while the spin axis of the α-Fe2O3(102) base layer was directed perpendicular to the film plane. The magnetization of ferrimagnetic CoFe2O4 layers was coupled perpendicularly to the spin axis of anitiferromagnetic α-Fe2O3 layers due to the exchange coupling at the interface between CoFe2O4 and α-Fe2O3.
Since the beginning of the 18th century A.D., an artificial iron oxide pigment (hematite, called “bengara” in Japanese) and having a beautiful yellowish red color, has been produced in Japan and applied to pottery, textiles and paintings. However, in 1965 the traditional “bengara” could not be produced anymore, mainly because of environmental pollution. The purpose of this study is to make clear the features of traditional “bengara” and to reproduce high quality “bengara” using modern high-purity reagents. Traditional “bengara” has been characterized as hematite containing a small amount of Al. The average size of the “bengara” particles is approximately 100 nm. The color becomes more yellowish-red with increasing Al content. A monophase of hematite prepared by heating a mixture FeSO4-7H2O and α-Al2O3 to about 680 °C included a small amount of Al substituted in a solid solution. The particle size greatly decreased as the heat treatment temperature was decreased: 100 nm at 770 °C but 50 nm at 650 °C. The color of the particles becomes more vivid as the temperature is decreased, but within bounds this color is independent of the amount of Al in solid solution.
We have investigated the growth of 3 ML (mono-layer) of Ag on Cu(111) for substrate temperatures from 170 through 640 K by using time of flight-impact collision ion scattering spectroscopy (TOF -ICISS). Two different types of epitaxial growth exist: Ag //Cu(type-n) and Ag //Cu (type-r).The growth modes of the Ag thin films on Cu(111) surfaces depend strongly on the temperature during deposition with the Ag(111) planes having a preferred orientation of either type-n growth mode or type-r growth mode as a function of theCu substrate temperature. The experimental results concerning Ag/Cu(111) show many similarities to those in the previous study of Au/Ni(111). This would suggest that an observed oscillation in the growth mode, dependent on the substrate temperature during deposition may a general phenomenon on solid surfaces, in cases of large misfit since it has now been seen for both Au/Ni(111) and Ag/Cu(111) systems.
Measurements of electron momentum density by positron annihilation are influenced by thepresence of defects in superconducting oxides. Both lifetime and Doppler broadening measurements are sensitive to the superconducting transition. Possible candidates for the defect species are discussed along with their role in modifying the positron response.
After the review of dopant redistribution phenomena observed during formation of near noble metal suicides, we describe the results of our recent experiments to get a better understanding of a mechanism of the dopant redistribution phenomenon in Si substrates. The key factors to understand the dopant redistribution are dopant segregation at the suicide/ Si interface due to lower solubility limit of dopants in suicides, enhanced diffusion of dopants into the Si substrate at much lower temperatures than the ordinary thermal diffusion, and electrical activation of the redistributed dopants. The results of As and carrier concentration measurements before and after Pd2Si formation to make clear the third factor show that the electrical activity of the redistributed As atoms in Si is strongly dependent on the initial activity before Pd2Si formation which is controlled by the temperature for the pre-annealing of As implanted Si.
Shrinkage of extrinsic dislocation loops introduced by As implantation and subsequent annealing have been observed after Pd2Si formation, which is a good evidence of vacancy generation during Pd2Si formation. The role of the vacancies and interstitials on the second factor, the enhanced diffusion, has also been discussed. Finally we list a few issues to be answered in future by more detailed works in order to get a complete understanding of the redistribution phenomenon.
Pd deposits on Ni(111) have been studied by low energy ion scattering spectroscopy. We found that two different types of epitaxial growth exist: Pd[11 2]//Ni[11 2] and Pd[11 2]//Ni[11 2] at substrate temperature of 300 K. The Pd(111) planes grow as mixed domains of 50 % each. Surface alloying of the Pd-Ni system was confirmed for deposition at 300 K in which Pd atoms displace first-layer Ni atoms, with an outward displacement of 0.4 Å with respect to first layer Ni atoms.
We have been developing a low energy Ne atom scattering system combined with a time-of-flight spectrometer for insulator surface structural analysis. Insulator surface structure is difficult to study because of charging effects during electron or ion beam bombardment. Structural analyses of insulator surfaces are very important in fundamental research as well as technology fields. In our system, charged ion beams of 2 keV-Ne+ are converted into neutral beams by charge exchange with the same element gas after the primary beam passes through a chopper. Other features of this system are pulsed beams, time-of-flight measurements, and a micochannel plate (MCP) detector is coaxially mounted along the primary beam. This is a home made equipment. We will show the detection systems, as well.
Thin films of a charge transfer complex, hepta-(tetrathiafulvalene) pentaiodide ( TTF7I5, TTF:I0-71 ), were prepared by double source evaporation of TTF and iodine. Crystalline films of TTF:I0-7i were obtained when substrate temperatures were kept between 0°C and 25°C. Orientation alignment of the crystalline films were affected by supply rate of iodine. By controlling the substrate temprature and the supply rate of iodine, highly oriented crystalline films were grown on mica substrates. It showed strong dichroism and anisotropic electrical propert ies.