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Photo-induced crawling motion of a crystal of 3,3'dimethylazobenzene (DMAB) on gold surfaces having different surface properties and various patterns was studied. DMAB crystals crawl continuously when exposed to UV and visible lig...
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Photo-induced crawling motion of a crystal of 3,3'dimethylazobenzene (DMAB) on gold surfaces having different surface properties and various patterns was studied. DMAB crystals crawl continuously when exposed to UV and visible lights simultaneously from different directions. On a gold surface functionalized by a thiol having a hydroxyl group at the terminal (16-hydroxy-1-hexadecanethiol (HOC16SH)), the crystals crawled with a relatively high velocity (ca. 4 mu m min(-1)), and they changed the crystal shape while keeping a distinct crystal face. On a gold surface functionalized by a thiol having an alkyl chain terminal (1-hexadecanethiol (C16SH)), the crawling was observed with a slower velocity (ca. 1.5 mu m min(-1)). However, the shape of the crystals became a droplet-like shape soon after the irradiation started, and the shape persisted during the motion. Light intensity dependence of the crawling velocity of the droplet-like crystal on this surface showed that UV light has stronger dependence for the motion than the visible light. On a substrate with a stripe pattern of alternating C16SH-modified gold and hexadecyltrimethylsilane (HDTMS)-modified glass, crystals crawled only on the surface of the C16SH-modified gold, which may be due to the wettability hysteresis at the surface. On a substrate with a stripe pattern of HOC16SH-modified gold and HDTMS-modified glass, crystals were attracted to the gold side. On a gold substrate with a periodic pattern of different height (ca. 50 nm) but having a uniform treatment with C16SH, crystals crawled up and down the steps without significant disturbance at the boundary of the step. Therefore, wettability of the surface has a greater impact on controlling the motion of the crystal than the surface structure. The present results not only unveil the crawling behavior on various surfaces but also offer a guide to controlling the motion toward applications for novel carriage vehicles to transport molecules/objects on a surface.
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Antiperovskites are a promising candidate structure for the exploration of new materials. We discovered an antiperovskite phosphide, LaPd3P, following our recent synthesis of APd(3)P (A = Ca, Sr, Ba). While APd(3)P and (Ca,Sr)Pd3P...
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Antiperovskites are a promising candidate structure for the exploration of new materials. We discovered an antiperovskite phosphide, LaPd3P, following our recent synthesis of APd(3)P (A = Ca, Sr, Ba). While APd(3)P and (Ca,Sr)Pd3P were found to be tetragonal or orthorhombic systems, LaPd3P is a new prototype cubic system (a = 9.0317(1) angstrom) with a noncentrosymmetric space group (I (4) over bar 3m). LaPd3P exhibited superconductivity with a transition temperature (T-c) of 0.28 K. The upper critical field, Debye temperature, and Sommerfeld constant (gamma) were determined to be 0.305(8) kOe, 267(1) K, and 6.06(4) mJ mol(-1) K-2 f.u.(-1), respectively. We performed first-principles electronic band structure calculations for LaPd3P and compared the theoretical and experimental results. The calculated Sommerfeld constant (2.24 mJ mol(-1) K-2 f.u.(-1)) was much smaller than the experimental value of y because the Fermi energy (E-F) was located slightly below the density of states (DOS) pseudogap. This difference was explained by the increase in the DOS at E-F due to the approximately 5 atom % La deficiency (hole doping) in the sample. The observed T-c value was much lower than that estimated using the Bardeen-Cooper-Schrieffer equation. To explain the discrepancy, we examined the possibility of an unconventional superconductivity in LaPd3P arising from the lack of space inversion symmetry.
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We evaluated the spatial variability of geochemical features, including trace-element cycles, associated with methane seepage in a knoll off Sakata (called Sakata Knoll) in the eastern Japan Sea. Seafloor observations from a remot...
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We evaluated the spatial variability of geochemical features, including trace-element cycles, associated with methane seepage in a knoll off Sakata (called Sakata Knoll) in the eastern Japan Sea. Seafloor observations from a remotely operated vehicle and environmental visualization around Sakata Knoll by an optical mapping device revealed large patches of white and gray microbial mats covering sediment in the depression on the top of the knoll. Push core samples were collected inside and a few meters outside microbial mats, and outside the gas hydrate-bearing areas. For these cores, the interstitial sulfate ion (SO42-) concentrations, sedimentary total organic carbon, total sulfur (TS), and trace-element contents, and bulk carbonate minerals delta C-13 were analyzed. In the entire core samples below the microbial mats and in sediments below 10 cm depth outside microbial mats, TS contents were substantially higher than those at the reference site, and bulk carbonate minerals delta C-13 was strongly negative (-20 parts per thousand to-40 parts per thousand ). These results imply that the formations of sulfide minerals and authigenic carbonates occur in the anoxic sediments via microbial anaerobic oxidation of methane (AOM) coupled with sulfate reduction. Although a rapid and linear decrease of interstitial water SO42-concentration in the sediments collected inside microbial mats supports the occurrence of AOM, there is no fall in SO42-concentration outside microbial mats, which may be explained by the higher upward flow of methane gas inside than outside the mats. The AOM-impacted sediments at Sakata Knoll were characterized by enrichments in Mo and As that were well correlated with TS contents and the authigenic iron fraction, and by strong enrichment of authigenic Mo relative to U, indicated by higher Mo/U ratios than those of seawater. These observations suggest that Mo and As are effectively transferred from the water column to AOM-impacted sulfidic sediments at Sakata Knoll via precipi-tation of particulate iron-manganese oxyhydroxides in the water column that have adsorbed Mo and As.
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Carbon nanotubes (CNTs) are of great interest to polymer scientists as reinforcements in polymer matrices to produce conductive thermoplastics. Unfortunately, their orientation distributions after the injection molding process hav...
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Carbon nanotubes (CNTs) are of great interest to polymer scientists as reinforcements in polymer matrices to produce conductive thermoplastics. Unfortunately, their orientation distributions after the injection molding process have been found to provide low interparticle contact and electrical conductivity. In this study, we attempt to improve these characteristics in CNT-reinforced polycarbonate (PC) composites produced by injection molding using both types of CNTs, namely, single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs, respectively). However, electrically conductive CNT networks were found to be re-tailored through post-processing annealing at high temperatures. For example, the conductivity of SWCNT(1 wt%)/PC was improved 1012 times with annealing. Herein, the electrical network of SWCNT-based polymer composites transformed after annealing was investigated for the first time in detail. Polarized Raman mapping clearly demonstrated the transition from aligned, unconnected CNTs before annealing to a randomly oriented interconnected network after annealing. Moreover, the annealing-induced expansion of the CNT electrical network path was directly visualized using the lock-in thermography technique, which clearly showed an increase in the degree of interconnection among CNTs in all regions of the molded parts from the skin to the core. Notably, the response of the composite to electromagnetic waves changed from absorption to reflection owing to this improved conductivity. The 3 wt% SWCNT/PC, which exhibited the highest electrical conductivity of 2.37E-01 S/cm also provided the highest electromagnetic interference (EMI) shielding effectiveness of 46.7-51.1 dB, providing its wide-ranging applicability in EMI pollution protection.
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To reduce microplastic (MP) discharge into the aquatic environment, it is necessary to properly identify its sources and amounts. Here, specific MP sources, i.e., personal care products (PCPs), fibers from clothes, and tirewear pa...
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To reduce microplastic (MP) discharge into the aquatic environment, it is necessary to properly identify its sources and amounts. Here, specific MP sources, i.e., personal care products (PCPs), fibers from clothes, and tirewear particles (TWPs) were focused, and MP generations from these sources in the Tokyo Bay watershed, Japan, were estimated based on statistical data on production and reported emission factors of the MP sources and executing considering uncertainty on the data. Potential annual MP emission into Tokyo Bay was estimated to be 10.2 & PLUSMN; 1.6, 38 & PLUSMN; 22, and 1500-1800 tons for PCPs, fibers, and TWPs, respectively. Emissions into Tokyo Bay by assuming MP density and diameter was estimated. For fiber, the fraction to potential emission was estimated at 1.0-2.8 %. This study contributes to determining potential discharge pathways. This will assist in the application of appropriate measures to reduce MP discharge into water bodies.
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Solid oxide fuel cells (SOFCs) are currently used as highly efficient devices, but further high power density is needed for their widespread commercialization. The present work reports high-performance nanocomposite cathode layer ...
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Solid oxide fuel cells (SOFCs) are currently used as highly efficient devices, but further high power density is needed for their widespread commercialization. The present work reports high-performance nanocomposite cathode layer and anode functional layer (AFL), and the exceptional improvement in power density of SOFCs achieved by applying these nanocomposite layers. For these layer materials, two types of nanocomposite par-ticles are synthesized via spray pyrolysis, i.e., strontium-doped samarium cobaltite (SSC) and samarium-doped ceria (SDC) for the cathode, and NiO and yttria-stabilized zirconia (YSZ) for the AFL, which are of submicrometer-scale secondary particles formed with nanometer-scale crystallites. Both the SSC-SDC nano -composite cathode layer and the Ni-YSZ nanocomposite AFL show three-dimensional ultrafine structures with highly active large triple-phase boundary region and conducting network pathways. The distribution of relax-ation times and fitting analysis for the anode-supported SOFCs reveals that these nanocomposite cathode and anode effectively improve the electrochemical reactions of each electrode by lowering the electrode polarization resistance. The maximum power density of such SOFCs reaches extremely high values of 4.96, 4.05, 2.68, 1.34, and 0.63 W cm-2 at 800, 750, 700, 650, and 600 degrees C, respectively.
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Trichloroacetic acid is known as one of the harmful disinfection byproducts with chlorine of tap water and is regulated according to legally binding standards in Japanese Drinking Water Quality Standards. We developed a high-purit...
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Trichloroacetic acid is known as one of the harmful disinfection byproducts with chlorine of tap water and is regulated according to legally binding standards in Japanese Drinking Water Quality Standards. We developed a high-purity trichloroacetic acid reference material, NMIJ CRM 4074-a, with certified purity as a traceability source of standard solution supplied under the Japan Calibration Service System (JCSS). As trichloroacetic acid is hygroscopic, water could be the main impurity. Although all impurities in the sample can be possibly detected by the freezing point depression method (FPD), it was unclear for trichloroacetic acid whether water was detected by FPD owing to evaporation of water from the sample during fusion. Therefore, we confirmed that water in trichloroacetic acid was detected as an impurity by FPD. The procedure was validated from an increment of purity by FPD due to reduction of water content and an agreement of purity by FPD with those by neutralization titrimetry (NT) and mass balance approach (MBA), both methods were based on different measurement principles from FPD. The certified value was determined to be (0.999 +/- 0.003) kg kg(-1) from the purity assay by FPD and NT, and uncertainties due to the homogeneity and stability of the CRM were included in the expanded uncertainty. The reliability of the certified value was verified by the agreement of purities by FPD, NT, and MBA.
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Various statistical approaches such as classical regression and modern machine learning methods have been applied to measurement data for estimating the status of manufacturing processes, which is now boosted by the movement of In...
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Various statistical approaches such as classical regression and modern machine learning methods have been applied to measurement data for estimating the status of manufacturing processes, which is now boosted by the movement of Internet of Things (IoT). In this study, we attempt to integrate an analytical tool model of surface roughness and measurement data of CNC turning to develop a modeling approach which does not depend too much on data, but also effectively uses existing analytical models. As in previous researches, we use cutting speed, feed rate, depth of cut and three acceleration components from an accelerometer to predict surface roughness. Co-Kriging method is employed to integrate the above measurements and a well-known model of surface roughness in turning. It was confirmed that the approach improved the prediction accuracy when only small amount of data is available for model construction. Meanwhile, the accuracy of ordinary Kriging method, which only depends on data, is suitable when measurement data sufficiently spans the parameter space, being expected that it may be rare in actual operations. We also attempted to detect outlier of measurements using the Co-Kriging method, which might be a non-trivial task when there is no additional information to evaluate the validity of the measurement data.
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In this study, a hygroelectric cell, which generates electricity based on variations in humidity using a deliquescent electrolyte solution partitioned by a cation-exchange membrane, was modeled. In addition, simulations were perfo...
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In this study, a hygroelectric cell, which generates electricity based on variations in humidity using a deliquescent electrolyte solution partitioned by a cation-exchange membrane, was modeled. In addition, simulations were performed to predict the power generated by the cell. The results of the simulations, which considered the evaporation and condensation rates of water and the water permeability of the ion-exchange membrane, which depend on the water activity, were in keeping with those obtained experimentally.
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This paper proposed using the linear response function (LRF) of Kohn-Sham orbitals for checking the convergence regarding thickness in periodic slab-and-vacuum model calculations. The effectiveness was demonstrated using the alkal...
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This paper proposed using the linear response function (LRF) of Kohn-Sham orbitals for checking the convergence regarding thickness in periodic slab-and-vacuum model calculations. The effectiveness was demonstrated using the alkaline earth metal oxide (001) surface. The calculated LRF decreases and converges to zero toward the opposite side of a slab. The proposed LRF scheme can be used as a guide to judge convergence of the slab thickness.
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