Advances in scanning transmission electron microscopy (STEM) techniques have enabled us to automatically obtain electron energy-loss (EELS)/energy-dispersive X-ray (EDX) spectral datasets from a specified region of interest (ROI) at an arbitrary step width, called spectral imaging (SI). Instead of manually identifying the potential constituent chemical components from the ROI, it is more effective and efficient to use a statistical approach for the automatic identification of the underlying chemical components and their spectra. This problem of automatic decomposition of chemical components can be formalized as a matrix factorization, which is a common problem setting in statistical machine learning. This paper first reviews several matrix factorization methods and then introduces our extension of a non-negative matrix factorization (NMF). The present NMF solves two problems: i) resolving overlapped spectral profiles, avoiding unnatural crosstalk, and ii) optimizing the number of chemical components. These effectiveness and comparisons with other matrix factorization methods are demonstrated using a real STEM-EELS dataset.
We successfully examined effects of pulverization and an addition of sintering aids on the orientation degree, sintering performances, and dielectric properties of sintered compacts of needle-like TiO2 particles. In the case of additive-free samples, an improvement in sintering performances was achieved by pulverization. However, the orientation degrees of these samples were decreased and calcination at high temperatures (≥ 1200 °C) was indispensable for obtaining an adequate relative density. On the other hand, by the addition of CuO-TiO2-Nb2O5-Ag2O type additives, the samples could be well sintered as much as 380 °C below their original sintering temperature with retaining the high orientation degrees. Moreover, high insulation resistances were achieved for samples with additives compared to that of additive-free samples and its relationship with the microstructures was discussed. Thus, this study provides an experimental investigation on improvements of sinterabilities and insulation properties of orientated TiO2 ceramics by the use of sintering additives.
Mn 3s→2p x-ray emission spectrum is measured at the Mn 2p1/2 photoabsorption maximum around 653 eV for polycrystalline La1−xSrxMnO3 with x from 0 to 1. A double-peak structure like the exchange splitting in the Mn 3s core-level photoemission spectrum is observed in the Mn 3s→2p1/2 emission spectrum. With increasing x, the splitting energy of the double-peak in the emission is nearly constant up to around x = 0.5 and then decreases until x = 1. This is consistent with the x-dependence of the Mn 3d electron number in doped manganite estimated in previous studies. It indicates that the splitting energy in the emission measures the Mn 3d spin moment or the Mn valence state of manganites. The probing depth of the method is about 100 nm.
The optical properties of porous Si terminated by various hydrophilic organic molecules were investigated to clarify the influence of the molecular length on the optical properties. In the case of porous Si terminated with hydrophilic organic molecules, surface oxidation of porous Si was restrained and the photoluminescence (PL) properties were more stable than those of the as-prepared sample. The PL of porous Si terminated with organic molecules was caused by the quantum size effect, which was confirmed on the basis of measured PL decay curves. The molecular length of the surface-terminated molecules did not affect the PL properties. Therefore, surface termination with hydrophilic organic molecules is an effective method to improve the stability of the optical properties of porous Si.
We studied the photoluminescence (PL) of porous Si powder via oxidation in distilled water and organic solvents of ethanol, acetone and hexane. Porous Si powder aged in an ethanol solution increased in PL intensity up to 50 times over 4 days. Even though the PL intensity of porous Si aged in acetone and hexane solutions also increased, the increase was smaller than that of seen in the ethanol solution. Porous Si powder oxidized in an ethanol solution shows the best improvement in PL intensity for all the used solvents. However, the PL intensity of porous Si aged in distilled water decreased. The PL intensity of porous Si aged in deaerated ethanol slowly increased indicating that the surface oxidation of porous Si was caused by the oxygen dissolved in the organic solvents. Oxidation of a porous Si surface strongly depends on the type of organic solvent.
Recent years, a few companies made Ti-Ni superelastic wire ropes. The advantages of Ti-Ni superelastic wire ropes are high damping capacity, long fatigue life, and large bending flexibility and large responsively. The aim of present study is to investigate the effect of design of the wire rope on stress hysteresis, superelastic strain and dissipated strain energy by using tensile tester. The shape of wire rope was 3x0.1 mm (3-strand wires), 3x0.14 mm, 3x0.2 mm, 7x0.1 mm (7-strand wires), 7x0.14 mm and 7x0.2 mm. Transformation temperatures were measured with a differential scanning calorimeter (DSC). The mechanical properties were measured by tensile test at 25 ̊C. Larger stress hysteresis and dissipated strain energy were observed for the wires with large diameter. The stress of stress induced martensitic transformation and hysteresis were increased with increase the number of wires in Ti-Ni wire rope. It was found that the best specimen to absorb vibration was the 7-strand wire ropes with a diameter of 0.2 mm.
The translational diffusion coefficient of water molecules in DPPC liposome/water dispersion systems was obtained by Pulsed Field Gradient (PFG) NMR method. Two types of diffusions of water molecules existing in dispersions were distinguished each other as the fast and the slow components by bi-exponential analysis of the diffusion process. The fast component exhibits likely to the pure water dynamics. On the other hand, the slow component shows two or three orders of magnitude smaller than the fast component. By the temperature and diffusion time dependences, the slow component was clearly characterized as hydrated water molecules interacting with the phospholipid membrane and moving with liposome particles. Above the main transition temperature of 1,2-dipalmitoyl-rac-glycero-3-phosphocholine (DPPC), the slow component showed a drastic increase in the diffusion coefficient and the tendency did not follow the liposome particle dynamics obtained by Stokes-Einstein relation. These results indicate that the fluidity and dynamic behavior of phospholipid membranes were abruptly changed according to the phase transition and dynamics of water molecules were treated as the probe. Both components show a typical "restricted diffusion" which means that the diffusion coefficient was dependent on the diffusion time, and this attribution provides a spatial information of such dispersion system.
Configurational polyhedora (CP) are hyperpolyhedra on multidimensional configuration space, whose vertices correspond to upper or lower value of correlation functions for all possible atomic configuration on given lattice. In classical systems where physical property including internal energy and elastic modulus can be a linear map with respect to structures considered, it is known that atomic configuration having highest (or lowest) physical quantity should always locate on one of the vertices at absolute zero temperature. The present study extend the idea of CP to finite-temperature property (especially, focusing on internal energy), and successfully provides demonstration of how temperature dependence of internal energy in equilibrium state for alloys can be characterized in terms of the spatial constraint on the system, and is interpreted in terms of the density of states for non-interacting system along specially selected coordination on configuration space.
In order to obtain fundamental data related to new wood machining technologies that utilized high-speed friction, this study investigated the characteristics of spruce (Picea sitchensis Carr.) surfaces when friction was applied using metal tools with various microscopic asperities. The results showed that spruce surface profiles smoothen when rubbed by metal tools with fine asperities and that varying characteristics could be imparted depending on the tool surface asperity shape. In addition, the transcription rate that evaluated by roughness parameter of tools and spruce surfaces increased as tool surface rougher when friction was applied parallel and perpendicular to the spruce surface, even though the wood surface became rougher. The amplitude of surface profile in transcribed spruce was different from that in used tool when the combination of the amplitude in wood before friction and metal tool was remarkably different. From the surface roughness results and rubbed surface observation, it was suggested that the asperity shape combination affected the properties transcribed onto the wood surface by high-speed friction.
Anhydrous FeF3 was prepared by drying in vacuum of FeF3•3H2O and surface oxidized FeF3 samples were obtained by the calcination of Anhydrous FeF3 at 473 – 773 K for 10 minutes - 3 hours under air. The obtained samples were characterized by use of X-ray diffraction, scanning electron microscopy. FeF3 became stable under atmosphere after oxidation at 673 K for more than 20 minutes. It was found that Fe2O3 was produced by calcination and covered the surface of FeF3 particles. In Charge-discharge measurements, the discharge capacity of these FeF3 samples was 100 - 225 mAh/g at 0.1 C. The discharge capacity for FeF3 sample calcined at 673 K for 20 min decreased with an increase of the discharge rate and the capacity at a high rate such as 3 C was maintained to be 130 mAh/g which was half value of the theoretical capacity of FeF3 cathode. The surface oxidation could improve the rate capability of FeF3 cathode.
We successfully synthesized a thin graphite film by microwave surface-wave plasma chemical vapor deposition and investigated the effect of UV light from the plasma during the film synthesis. The quality of the film was compared between the case where UV light was irradiated from the plasma and the case where the UV light was blocked. The quality was also evaluated by Raman scattering spectroscopy. There were more defects in the thin graphite film prepared with UV light irradiation than with the UV light blocked. These results suggest that during the synthesis of the thin graphite film, UV light affects its crystallinity. However, charged particles from the plasma had no effect on the quality. Cross-sectional transmission electron microscopy revealed that the thin graphite film consisted of approximately 20 layers.
A low hydrogen-diluted and low gaseous-pressure monosilane plasma (hydrogen to monosilane flow rate ratio of 3.3 ≤ [H2]/[SiH4] ≤ 10, 80 Pa) was applied to the fast chemical-vapor deposition of solar-cell-grade hydrogenated microcrystalline silicon (μc-Si:H) by using an ultrahigh-vacuum very-high-frequency (105 MHz) hollow-electrode-enhanced glow-plasma transfer technique (VHF-HEEPT). The deposition of a well-crystallized and photosensitive μc-Si:H thin film with a preferential <110> crystal orientation was achieved at a growth rate of 5.0 nm/s and a [H2]/[SiH4] ratio of 3.3 by applying a VHF power of 100 W (the highest available power in this work). The same deposition conditions were applied to grow the i (intrinsic)-layer of an n−i−p-type single-junction solar cell. The photo-conversion efficiency of the solar cell was 3.4% with no degradation of the open-circuit voltage (0.44 V) and its fill factor was 54.7%. The crystallographic structure of the solar cell revealed that the i-layer (μc-Si:H) consisted of almost the same <110>-preferential crystallite and columnar structure as that of the solar cell, in which the i-layer was deposited under high hydrogen-diluted conditions ([H2]/[SiH4] = 26.7). These results indicate that a low hydrogen-diluted and low gaseous-pressure monosilane plasma is applicable to the fast thin-film deposition of solar-cell-grade μc-Si:H by using the VHF-HEEPT system. The depth profiles of phosphorus and oxygen concentrations demonstrated that the i-layer of the solar cells contained larger amounts of these elements than the single i-layer deposited on a glass substrate, especially in the boundary region with the substrate. Further development of both the HEEPT system and film deposition conditions would be effective for improving the performance of solar cells.
Because bamboo flour shows a rather more fiber-like shape rather than wood flour does, it is expected that a combination of bamboo flour and phenol exhibits higher mechanical properties, as compared to those of wood ceramics. After a bamboo flour/phenol resin composite was carbonized at 800°C and 1,500°C, its bending properties were investigated. Results show that the bending properties of the carbonized composite are comparable to those of wood ceramics. Regarding the effects of carbonizing temperatures, the composite elastic modulus carbonized at 1,500°C shows a higher value than that carbonized at 800°C. In addition, the electron probe microanalysis (EPMA) was conducted. The result of 1,500°C shows that silicon carbide (SiC) occurs finely and dispersedly. The bending modulus obtained at 1,500°C is improved probably because such occurrence of SiC makes it stiffer. In this paper, wear properties of the composite were investigated further.