The preparation of copper fine particle paste and its application as the inner electrode material of a multilayered ceramic capacitor

Well size-controlled copper fine particles (diameter: 100-300?nm) were used as the inner electrode material of multilayered ceramic capacitors (MLCCs). The particles were dispersed in terpineol to form a printing paste with 50?wt% copper particles. The MLCC precursor modules prepared by the layer-by-layer printing of copper and BaTiO(3) particles were cosintered. Detailed observation of the particles, paste, and MLCCs before and after sintering was carried out by electron microscopy. The sintering temperature of Cu-MLCC was as low as 960?°C. The permittivity of these MLCCs was successfully measured with the copper inner layers.     

A novel PCR method for quantification of buckwheat by using a unique internal standard material

A novel quantitative and specific method for detection of buckwheat, a known food allergen, in diverse food materials was developed by using a unique internal standard to compensate for the variability in DNA extraction and amplification efficiencies. The method was based on a real-time PCR targeting the internal transcribed spacer region of Fagopyrum spp. and was designed to detect both cultivated and wild buckwheat, because wild buckwheat might be potentially allergenic. As the internal standard material, ground seeds of statice (Limonium sinuatum) were added to food samples prior to DNA extraction, and the amount of statice DNA measured by real-time PCR was used to standardize the buckwheat content. Statice, an ornamental plant, was chosen as the internal standard material because it was readily available and was inferred to be least likely to be commingled in foods. The specificity of the PCR system was tested against commonly used food materials of plant origin. Quantitative results expressed in buckwheat protein concentrations (mean +/- standard deviation) for various food samples prepared to contain 10 ppm (wt/wt) of buckwheat flour (corresponding to 1.2-microg/g [ppm] buckwheat protein) ranged from 0.7 +/- 0.2 (rice) to 0.9 +/- 0.4 (wheat) and for 100-ppm (wt/wt) samples (12-microg/g [ppm] buckwheat protein) from 7.7 +/- 1.0 (pepper) to 9.8 +/- 0.5 (wheat) microg/g (ppm). The method's accuracy, sensitivity, and specificity were considered sufficient for detection of buckwheat contamination at the level required for compliance with the Japanese Food Allergen Labeling Regulation.     

Formation of Exclusive Al2O3 Scale on Nb and Nb-Rich Alloys by Two-Step Oxygen–Aluminum Diffusion Process

External Al₂O₃ scale formation behavior by a diffusion aluminizing process on Nb and Nb–X (X?=?Mo, Re, and Ta) alloys with different oxygen solubilities was investigated. The oxygen content in Nb and Nb–X alloys was controlled by oxygen diffusion treatment at 1,100?°C using Nb/NbO mixture. Nb–aluminide, NbAl₃ and Nb₂Al, layers were developed on the low-oxygen Nb substrate by an aluminum diffusion treatment using Al/Al₂O₃/NH₄Cl mixture at 1,100?°C; whereas an adhesive Al₂O₃ scale developed on the Nb substrate with higher oxygen content. The alloy oxygen content decreased by an addition of Ta, Mo and Re, in this order, and the decrease in alloy oxygen content resulted in the transition of Al₂O₃ formation from external scale to internal precipitates. This transition was not observed when low Al activity powder mixture, Ni50Al/Al₂O₃/NH₄Cl, was used for Al diffusion process, and only external Al₂O₃ scale was developed on all samples. In the present study, the effects of oxygen solubility limit, oxygen content, and the activity of Al in diffusion process on the formation of Al₂O₃ scale will be discussed.     

Dependence of vacancy concentration on morphology of helium bubbles in oxide ceramics

Since the formation of helium bubbles degrades swelling property and thermal conductivity of minor actinide-containing mixed oxide (MA-MOX) fuel, it is essential to understand the conditions of the bubble formation. In order to examine the dependence of vacancy concentration on morphology of helium bubbles, helium was infused into (Zr,Fe)O_2?x. The oxygen vacancy concentration was controlled by addition of solute Fe³⁺ into ZrO₂. Helium was infused by hot isostatic pressing. The helium-infused specimens were observed by field emission scanning electron microscopy (FE-SEM) and field emission transmission electron microscopy (FE-TEM). In addition, X-ray fluorescence, X-ray diffraction analysis, conversion electron yield–X-ray absorption near-edge structure and FE-SEM/EDX (energy dispersive X-ray) analyses were also made to interpret the results of microstructure observations. As a result of the helium infusion treatment, numerous 0.5–10 nm bubbles were observed and its number density clearly depended on oxygen vacancy concentration. On the other hand, sizes of the helium nano-bubbles in all specimens were almost constant.     

Chitin nanofibers: preparations, modifications, and applications

Chitin nanofibers are prepared from the exoskeletons of crabs and prawns by a simple mechanical treatment after the removal of proteins and minerals. The obtained nanofibers have fine nanofiber networks with a uniform width of approximately 10-20 nm and a high aspect ratio. The method used for chitin-nanofiber isolation is also successfully applied to the cell walls of mushrooms. They form a complex with glucans on the fiber surface. A grinder, a Star Burst atomization system, and a high speed blender are all used in the mechanical treatment to convert chitin to nanofibers. Mechanical treatment under acidic conditions is the key to facilitate fibrillation. At pH 3-4, the cationization of amino groups on the fiber surface assists nano-fibrillation by electrostatic repulsive force. By applying this finding, we also prepared chitin nanofibers from dry chitin powder. Chitin nanofibers are acetylated to modify their surfaces. The acetyl DS can be controlled from 1 to 3 by changing the reaction time. An acetyl group is introduced heterogeneously from the surface to the core. Nanofiber morphology is maintained even in the case of high acetyl DS. Optically transparent chitin nanofiber composites are prepared with 11 different types of acrylic resins. Due to the nano-sized structure, all of the composites are highly transparent. Chitin nanofibers significantly increase the Young's moduli and the tensile strengths and decrease the thermal expansion of all acrylic resins due to the reinforcement effect of chitin nanofibers. Chitin nanofibers show chiral separation ability. The chitin nanofiber membrane transports the d-isomer of glutamic acid, phenylalanine, and lysine from the corresponding racemic amino acid mixtures faster than the corresponding l-isomer. The chitin nanofibers improve clinical symptoms and suppress ulcerative colitis in a DSS-induced mouse model of acute ulcerative colitis. Moreover, chitin nanofibers suppress myeloperoxidase activation in the colon and decrease serum interleukin-6 concentrations.     

Homology-Based Interactions between Small RNAs and Their Targets Control Dominance Hierarchy of Male Determinant Alleles of Self-Incompatibility in Arabidopsis lyrata

Self-incompatibility (SI) is conserved among members of the Brassicaceae plant family. This trait is controlled epigenetically by the dominance hierarchy of the male determinant alleles. We previously demonstrated that a single small RNA (sRNA) gene is sufficient to control the linear dominance hierarchy in Brassica rapa and proposed a model in which a homology-based interaction between sRNAs and target sites controls the complicated dominance hierarchy of male SI determinants. In Arabidopsis halleri, male dominance hierarchy is reported to have arisen from multiple networks of sRNA target gains and losses. Despite these findings, it remains unknown whether the molecular mechanism underlying the dominance hierarchy is conserved among Brassicaceae. Here, we identified sRNAs and their target sites that can explain the linear dominance hierarchy of Arabidopsis lyrata, a species closely related to A. halleri. We tested the model that we established in Brassica to explain the linear dominance hierarchy in A. lyrata. Our results suggest that the dominance hierarchy of A. lyrata is also controlled by a homology-based interaction between sRNAs and their targets.     

Effects of Tl-filling into the voids and Rh substitution for Co on the thermoelectric properties of CoSb3

In order to enhance the thermoelectric (TE) properties of CoSb₃, we tried to reduce the lattice thermal conductivity (κ_lat) by filling Tl into the voids and substitution of Rh for Co. We prepared polycrystalline samples of Tl_x(Co_1−yRh_y)₄Sb₁₂ (x = 0, 0.05, 0.10, 0.15, 0.20 and y = 0.1, 0.2) and examined their TE properties from room temperature to 750 K. All the samples indicated negative values of the Seebeck coefficient (S). Both the electrical resistivity and the absolute values of the S decreased with increasing the Tl-filling ratio. The Tl-filling and Rh substitution reduced the κ_lat, due to the rattling and the alloy scattering effects. The minimum value of the κ_lat was 1.54 W m⁻¹ K⁻¹ at 550 K obtained for Tl_0.20(Co_0.8Rh_0.2)₄Sb₁₂. Tl_0.20(Co_0.8Rh_0.2)₄Sb₁₂ exhibited the best TE performance; the maximum value for the dimensionless figure of merit ZT was 0.58 at around 600 K.     

Photocatalytic effects of plasma-heated TiO2−x particles under visible light irradiation

The photocatalytic characteristics of partially reduced TiO₂ (TiO_2?x ) by plasma treatment and plasma-heated treatment were investigated in the visible-light region. For the visible-light photocatalytic activity of TiO_2?x , plasmaheated treatment shows stronger than plasma treatment significantly. The TiO_2?x by plasma-heated treatment shows broader red-shifted absorption bands than one by plasma treatment in the visible-light region. The surface color of TiO_2?x by plasma treatment and plasma-heated treatment changed from white to sky blue, and to navy, respectively. After exposure to air, the surface color of TiO_2?x changed from sky blue to white for plasma treatment and from navy to beige for plasma-heated treatment.