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The Fukushima Daiichi and Daini Nuclear Power Plant workers experienced multiple stressors as both victims and onsite workers after the 2011 Great East Japan Earthquake and subsequent nuclear accidents. Previous studies found that disaster-related exposures, including discrimination/slurs, were associated with their mental health. Their long-term impact has yet to be investigated.
A total of 968 plant workers (Daiichi, n = 571; Daini, n = 397) completed self-written questionnaires 2–3 months (time 1) and 14–15 months (time 2) after the disaster (response rate 55.0%). Sociodemographics, disaster-related experiences, and peritraumatic distress were assessed at time 1. At time 1 and time 2, general psychological distress (GPD) and post-traumatic stress response (PTSR) were measured, respectively, using the K6 scale and Impact of Event Scale Revised. We examined multivariate covariates of time 2 GPD and PTSR, adjusting for autocorrelations in the hierarchical multiple regression analyses.
Higher GPD at time 2 was predicted by higher GPD at time 1 (β = 0.491, p < 0.001) and discrimination/slurs experiences at time 1 (β = 0.065, p = 0.025, adjusted R2 = 0.24). Higher PTSR at time 2 was predicted with higher PTSR at time 1 (β = 0.548, p < 0.001), higher age (β = 0.085, p = 0.005), and discrimination/slurs experiences at time 1 (β = 0.079, p = 0.003, adjusted R2 = 0.36).
Higher GPD at time 2 was predicted by higher GPD and discrimination/slurs experience at time 1. Higher PTSR at time 2 was predicted by higher PTSR, higher age, and discrimination/slurs experience at time 1.
High-velocity compact cloud (HVCC) is a peculiar category of molecular clouds detected in the central molecular zone of our Galaxy (Oka et al. 1998, 2007, and 2012). They are characterized by compact appearances (d < 5 pc) and very large velocity widths (Δ V > 50 km s−1). Some of them show high CO J=3–2/J=1–0 intensity ratios (≥ 1.5), indicating that they consist of dense and warm molecular gas. Dispite a number of efforts, we have not reached a comprehensive interpretation of HVCCs. Recently, we detected an extraordinaly broad velocity width feature, the ‘Bullet’, in the molecular cloud interacting with the W44 supernova remnant. The Bullet shares essential properties with HVCCs. Because of its proximity, a close inspection of the Bullet must contribute to the understanding of HVCCs.
Massive stars in a certain mass range (20 – 40M⊙) may form low mass black holes after supernova explosions. In such massive stars, fall back of ~ 0.1M⊙ materials onto a black hole is expected due to a deep gravitational potential or a reverse shock propagating back from the outer composition interface. We study hydrodynamical disk accretion onto a new-born low mass black hole in a supernova using the SPH (Smoothed Particle Hydrodynamics) method.
We synthesized viscous precursors to indium gallium zinc oxide (IGZO) using three kinds of alcoholamines, ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA), by a simple process. The viscous precursors are obtained just by vigorous stirring of alcoholamine and urea in an aqueous solution containing the metal nitrates during heating at 150-160 °C. The precursor containing EA (EA-precursor) is a pale-orange suspension containing aggregates of the metal hydroxides and shows pseudoplastic flow. The precursors containing DEA (DEA-precursor) and TEA (TEA-precursor) are transparent pale-yellow and dark-orange sols, respectively. They give Newtonian flow in the lower shear rate and pseudoplastic flow in the higher shear rate. Higher concentration of metal salts leads to higher viscosity of the precursors. According to thermogravimetry-differential thermal analysis (TG-DTA) for the EA- and DEA-precursors, evaporation of alcoholamine occurs at around each boiling point and subsequently formation of metal oxides occur at around 300 °C. In the case of the TEA-precursor, formation of metal oxides occurs before pyrolysis of TEA attributed to the higher boiling point of TEA. The thin IGZO film, which is prepared by spin-coating of the diluted DEA-precursor and subsequent sintering at 450 °C for 30 min, shows 0.02 cm2 ·V-1s-1 of the mobility and 10-5 of the on/off ratio. The highly viscous DEA-precursor containing high concentration of metal ions allows patterning in an area of 100 cm2 onto a surface of a silicon wafer with screen printing.
Hot core chemistry, characterized by the evaporation of icy mantle molecules from dust grains and subsequent gas-phase chemistry, seems ubiquitous in hot, dense clouds. Hot core molecules have been observed, not only in high-mass star-forming regions, but also in protoplanetary disks, shocks in young stellar outflows, and so on. Here, we study grain-surface chemistry and chemistry in hot gas in disks and outflows. Our results suggest that observations of molecular lines by the forthcoming ALMA and other facilities will give us information on, for example, grain-surface chemistry in the outer disk, turbulent mixing in the inner disk, and the physical and chemical conditions at the launching points of outflows.
We present the initial results of a spectral line survey of L1157 B1 with the Nobeyama 45 m telescope. So far, we have covered the frequencey range of 13.7 GHz (82.0–94.5 GHz and 96.3–97.5 GHz), and have detected 22 species including CH3CHO, HCOOH, HCOOCH3, HNCO, NH2CHO, CH3CN, and CCS. We have also detected the line of CH2DOH. These results demonstrate rich chemistry in this shocked region, which would mainly originate from evaporation of ice mantles by means of shocks.
Carrier transport properties and electronic structure of an n-type transparent oxide semiconductor, InGaO3(ZnO)5, were investigated using single-crystalline thin films. Room-temperature Hall mobility strongly depends on carrier concentration, and rapidly increased from ∼ 2 cm2(Vs)-1 to > 10 cm2(Vs)-1 around the carrier concentration (Nth ∼3 × 1018 cm−3. This change is associatedwith insulator-metal transition. These results are explained by a model similar to Anderson localization, in which shallow semi-localized states are formed originating from random distribution of Ga3+ and Zn2+ ions in the intrinsic crystal structure of InGaO3(ZnO)5. The present conclusion suggests that electron densities larger than Nth are necessary to attain high performances in drift carrier devices fabricated using InGaO3(ZnO)5. It was demonstrated that transparent filed-effect transistors exhibited good performances such as a “normally-offcharacteristics”, an on/off current ratios as large as 105 and a field-effect mobility ∼80 cm2(Vs)-1when high-k material, amorphous HfOx, was used as a gate insulator.
A novel characterization method is applied to study the evolution of microstructures during densification of silicon nitride ceramics. This characterization method involves an immersion liquid for making green and sintered bodies transparent, and a subsequent direct optical microscopic examination. Granules were prepared with the spray drying processand formed into green bodies by CIP. After sintering at various temperatures, the specimens were examined for microstructural evolution. Large pores were located at the center and boundary regions of granules left in the green bodies; they were not removed by densification and resulted in large pores in the sintered body, possibly forming fracture origin in ceramics.
SiO2 thin firms were fabricated in a remote electron cyclotron resonance (ECR) plasma by tctraethoxysilane (TEOS) as the silicon source. Oxygen was used as the plasma gas. A mesh was placed between the TEOS gas outlet and the substrate. In the present investigation a-SiO2 films were deposited with and without the mesh and film properties were studied comparatively. The deposition rate increased when the mesh was attached. The optimum deposition rate is observed when the mesh voltage was zero, that is the mesh was grounded. The deposition rates of both methods were also dependnt on the TEOS flow rate, applied microwave power and the substrate temperature. These three parameters have significant roles in controlling the film quality. Good quality SiO2 films can be obtained with a higher deposition rate when a mesh is attached.
Atomistic simulation employing many-body central-force potentials was performed to elucidate the diffusion mechanisms in the bulk and at lamellar interfaces assuming a vacancy mechanism. First the self- diffusion of Ti and Al in stoichiometric structures was studied. It was found that the diffusion was faster along lamellar interfaces than in the bulk; the effective activation energy for the diffusion coefficient is about ∼15% lower. The simulations were then extended to investigate diffusion along lamellar boundaries with segregated Ti which is likely in Ti rich alloys. The surprising result is that diffusion remains practically unchanged when compared with the stoichiometric case. The reason is that while the path controlling the diffusion is different, the corresponding effective formation and migration energies are practically the same as in the stoichiometric case.
We have developed a novel growth method for single-crystalline film of natural superlattice oxides and named the method “Reactive Solid-Phase Epitaxy (R-SPE).” Single-crystalline thin films of homologous series In-GaO3(ZnO)m (m=integer) are fabricated by the R-SPE method and its growth mechanism, especially a role of ZnO epitaxial layer, is clarified. High-temperature annealing of bi-layer films consisting of an amorphous InGaO3(ZnO)5 layer deposited at room temperature and an epitaxial ZnO layer on YSZ substrate allows for the growth of single-crystalline film with a controlled chemical composition. The ZnO layer plays an essential role in determining the crystallographic orientation, while the thickness ratio between the two layers controls the film composition.
Transparent metal-insulator-semiconductor field-effect transistors (MISFETs) were fabricated using a single-crystalline thin film of an n-type transparent oxide semiconductor, a homologous compound InGaO3(ZnO)5, grown by a reactive solid phase epitaxy method. The transparent MISFET exhibited good performances with “normally-off characteristics”, “an on/off current ratio as large as 105” and “insensitivity to visible light”. Field-effect mobility was about 2 cm2(Vs)-1, which is larger than those reported previously for MISFETs fabricated in transparent oxide semiconductors. These improved performance is thought to result from the low defect density and intrinsic-level carrier concentration of the single-crystalline InGaO3(ZnO)5 film.
Stress adjustment and improvement of electrical characteristics in film bulk acoustic wave resonator (BAW) have been successfully carried out in 1.8GHz range by using a multi-layer structure of ZnO / Al2O3 / SiO2. The BAW resonator, designed on secondary harmonics at about 1.8GHz, has Al / ZnO / Al / Al2O3 / SiO2 structure. ZnO and SiO2 thin films have a negative and a positive temperature coefficient of sound velocity, respectively. So temperature coefficient of frequency (TCF) of the BAW resonator can be controlled by the thickness ratio of ZnO and SiO2 thin films. Since both ZnO and SiO2 have compressive stress, and Al2O3 has tensile one, the stress of the membrane is reduced by combining these thin films so that the membrane can avoid deformation. The BAW resonator, with thickness of ZnO / Al2O3 / SiO2=1.2 /0.45/1.25 microns, was designed by finite element method (FEM) simulation and fabricated. The value of quality factor (Q factor) and the TCF of the BAW resonator were realized over 1000 and −20 ppm/degree C, respectively. The Q of ZnO / Al2O3 / SiO2 structure was higher than that of ZnO / SiO2 one with keeping small TCF.
We have succeeded in making an 870MHz-range thin film bulk acoustic wave (BAW) resonator that has a small temperature coefficient of frequency (TCF) using secondary harmonics. The 870MHz-range BAW resonator has been requested to have nearly zero TCF, because it will be used in an oscillator for remote keyless entry systems. The BAW resonator has composite structure that consists of Al electrodes and ZnO/SiO2. We directed our attention to the fact that ZnO and Al have negative TCF, and SiO2 has a positive one. It is theoretically possible to make zero TCF BAW resonators by optimizing the thickness ratio of ZnO and SiO2. However, using fundamental resonance, TCF is so sensitive to the thickness ratio that it cannot be easily controlled by MEMS techniques. We founds in finite element method simulation and confirmed by experiment that the TCF of secondary harmonics has a local minimum when changing the ZnO/SiO2 thickness ratio. As the result, a nearly zero TCF resonator without strict control of ZnO/SiO2 thickness ratio has been realized by adopting Al/ZnO/SiO2/ZnO/Al/SiO2 structure and combining thermal oxidized Si and sputtered SiO2. The resonator has the TCF of -1.86ppm/degree in the range of −40 to 85 degrees centigrade.
In-situ reflection high energy electron diffraction total reflection angle X-ray spectroscopy (RHEED-TRAXS) was performed to monitor alloy composition at the surface during growth of nitrides by RF-MBE for the first time. TRAXS signal of the GaLα line is found to be more sensitive to the composition at the surface than the GaKαline. A difference in the composition of layer adsorbed on the surface and the solid alloy layer has been identified.
Silica film coatings were demonstrated using photo-chemical vapor deposition with a 172-nm Xe excimer lamp. Tetraethoxyorthosilicate (TEOS) molecules were successfully dissociated into SiO2+2C2H5-OH+;(residual C and H) with the 7.2-eV photons. The films were deposited onto a quartz or Al203 single crystal substrate with the deposition rate of 1 nm/min. The films were uniform and smooth enough for optical applications.
SiO2 thin films were deposited on automobile plastics at low temperatures using a microwave activated ECR plasma. Oxygen was used as the plasma gas while tetraethoxysilane (TEOS) was used as the source gas which was introduced into the downstream. In the present investigation high quality SiO2 films were deposited on polycarbonate (PC) and polypropylene (PP) substrates with and without a mesh and the characteristics of hard coating films were studied. The film growth rate increases with the decrease of substrate temperature when a mesh is inserted into the plasma. The irregularities of polymer surfaces could be planarized by the deposition of 1.0 μm thick SiO2 film. The dynamic hardness of PC and PP are increased by the deposition of SiO2 film, however, films deposited on PP is seen to be cracked while that of on PC is crack-free.
A thin film bulk acoustic wave resonator (TBAR) has been fabricated using a ZnO thin film on a SiO2 diaphragm by MEMs techniques. The ZnO/SiO2 structure TBAR can be designed to cancel a temperature coefficient of frequency (TCF) by the ZnO/SiO2 thickness ratio, because the TCF of ZnO is negative, and that of SiO2 is positive. The ZnO thin film on the SiO2 shows a c-axis orientation almost equivalent to that of the ZnO thin film on a glass substrate by RF sputtering. However, the crystallinity of the ZnO thin film is influenced by the surface conditions of substrates. ZnO thin films have been deposited on Au/Cr, Au/NiCr and Au/Ti. The Au/Ti/ZnO/Au/Ti/SiO2 structure TBAR shows the best resonant characteristics in this experiment. The resonant characteristics of the TBAR depend on the crystallinity of the ZnO thin film. The resonant resistance of the TBAR at 205MHz using a Au/Ti under electrode is about 10% less than that using an Au/Cr electrode. The x-ray diffraction result shows that the crystallinity of ZnO is greatly influenced by the crystallinity of the lower electrode. The buffer layer between an Au electrode and substrate has an influence on both the crystallinity of the ZnO thin film and the resonant characteristics of the TBAR through the Au electrode.
Compression tests were performed on specially-oriented PST TiAl crystals to which strain gages were attached in order to precisely measure the three axial strains in the samples during deformation. It was found that all samples deform by plane strain except when the compression axis is nearly perpendicular to the lamellar planes. This measurement technique was used to determine the orientations in which the various slip systems are operative in PST samples, and this, in turn was employed to explain the shape of the flow stress vs. orientation curve. An important component of this explanation is the fact that slip of ordinary dislocations and twinning are closely coupled in this material, implying that the twinning must occur relatively slowly-at about the same rate that ordinary dislocations move. Atomistic calculations have shown that a slow twinning process is to be expected in this material at low temperatures, perhaps even by a thermally activated process.