Dynamics of annular bright field imaging in scanning transmission electron microscopy

We explore the dynamics of image formation in the so-called annular bright field mode in scanning transmission electron microscopy, whereby an annular detector is used with detector collection range lying within the cone of illumination, i.e. the bright field region. We show that this imaging mode allows us to reliably image both light and heavy columns over a range of thickness and defocus values, and we explain the contrast mechanisms involved. The role of probe and detector aperture sizes is considered, as is the sensitivity of the method to intercolumn spacing and local disorder.     

Improvement of functional properties of whey soy protein phosphorylated by dry-heating in the presence of pyrophosphate

The physicochemical and functional properties of a whey soyprotein (WSP), which was phosphorylated by dry heating, were investigated. The phosphorus content of WSP was 0.85 g/100 g by dry-heating at pH 4.0 for 5 days in the presence of pyrophosphate. ³¹P NMR spectral data suggested that the serine and sugar of WSP were phosphorylated. Although changes in the random coil structure of WSP measured by circular dichroism were mild, increased surface hydrophobicity and decreased tryptophan fluorescence intensity were observed following phosphorylation. Phosphorylation improved the stability against heat-induced insolubility, emulsifying properties, foaming properties, water absorption capacity, and oil absorption capacity of WSP. These results suggested that dry-heating phosphorylation is a useful method for improving the functional properties of WSP.     

Magnetic-field angle dependent critical current densities and flux pinning in commercial YBCO tapes at liquid nitrogen temperatures

The magnetic-field angle dependence of critical current densities J_c(H,θ) in commercial YBCO tapes grown by MOCVD and MOD was examined at liquid nitrogen temperatures. We first measured J_c(H,θ) in MOCVD-YBCO tapes at 70 and 77.3 K in fields up to 2 T using both transport and inductive (the third harmonic voltage) methods and compared the results. It was observed that, in low magnetic fields, the transport measurements gave higher J_c than the inductive ones; however, in high fields they agreed well, which is well explained by the effects of weak links due to low-angle grain boundaries. We then investigated J_c(H,θ) in MOCVD- and MOD-YBCO tapes at 77.3 K in fields up to 2 T. All the tapes exhibited peaks at H//ab in the shape of Mount Fuji, which shows that small random pinning plays a major role. However, an anisotropic scaling analysis showed that the flux pinning mechanisms in those tapes were different, resulting in distinctive angular behaviors of J_c(H,θ). It is suggested that the difference in the flux pinning mechanisms of the two types of tapes came from the different sizes of point defects originating from the growing processes.     

Ni-Zn ferrite films synthesized from aqueous solution usable for sheet-type conducted noise suppressors in GHz range

Ni_0.2Zn_0.3Fe_2.5O₄ films (1–5 μm thick) were deposited by spin spray ferrite plating from an aqueous solutions onto polyimide sheets at 90^∘C. Their peel test and high-frequency permeability as well as noise suppression effects were investigated. The oxygen plasma treatment on polyimide sheet surface improved the film adhesion. There was not visible crack on the bended film surface for the Ni-Zn ferrite film thinner than 2 μm and was not peeled off even after the bending test of a million times. The films exhibited excellent high-frequency permeability profile and a natural resonance frequency (where the imaginary permeability reaches a maximum) f _r was 370 ± 30 MHz. The transmission loss increased with the film thickness, reaching the maximum Δ P _loss = 70% at 8 GHz for the 5 μm-thick film. The reflection loss in the measured frequency range was S ₁₁ < 10 % which is small enough for films to be used as the conducted noise suppressors. The value of Δ P _loss obtained for the 5-μm thick film was about 15% higher than that (Δ P _loss = 55 %) attained by the commercialized 50-μm thick noise suppressing sheet.     

Mechanism of capacitance aging under DC-bias field in X7R-MLCCs

Capacitance aging under DC electric fields has been studied on multilayer ceramic capacitors (MLCCs) with the X7R characteristics. The capacitance change with time was divided into two stages, the first- and the second-stage. The first-stage was due to the nonlinear permittivity of dielectrics and it should not be involved in the aging phenomenon. The second-stage depended on the MnO content, grain size and firing condition of dielectrics. From the behavior of the second-stage, it was concluded that the capacitance aging was caused by the 90-degree domain switching in BaTiO₃ in the core. The first-stage was due to the nonlinear permittivity but the domain switching was also included in the first-stage if the domain walls moved by the first application of DC field. The change in the aging behavior with the intensity of DC field could be explained by separating capacitance change into the nonlinear permittivity and the domain switching according to the mechanism proposed in this study.     

Combined rectifying system including double-series capacitor-smoothed diode rectifier and series active filter

This paper proposes a new rectifying system consisting of a series active filter and a double-series three-phase 12-pulse diode rectifier. The supply current in the proposed system has a sinusoidal wave shape because the series active filter suppresses the current harmonics produced by the diode rectifier. Since almost no 5th and 7th harmonics are produced by the double-series 12-pulse diode rectifier, the required peak rating of the series active filter is only 7% of the diode rectifier. In this paper, the control scheme and operating characteristics of the series active filter are theoretically and experimentally discussed. A novel conception that connection of a parallel capacitor to each diode of the rectifier makes a great contribution to reducing the required rating of the series active filter is also presented and verified by some experimental results. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(1): 85–94, 1997     

Immunoassay using poly-tetrafluoroethylene microstructure in organic solvent

This paper reports the first application of poly-tetrafluoroethylene (PTFE) microstructure, which fabricated by synchrotron radiation induced photo-evaporation process, to enzyme-linked immunosorbent assay. The advantages of PTFE microstructure for the development of lab-on-a-chip due to the extremely high-aspect ratio microstructure and chemical stability of PTFE is discussed. The results of immunoassay shows the successful detection of analyte (mouse IgG) with detection range with 0–100 ng/ml. This result suggests the successful immobilization of antibody (anti-mouse IgG goat antibody) onto the X-ray exposed surface of PTFE microstructure and successful demonstration of antigen–antibody reaction in the PTFE microstructure. We also demonstrated the detection of polychlorinated biphenyl (PCB). As the result of demonstration, we successfully detected PCB with ranging analyte concentration of 0.1–10 ng/ml.     

Influence of CuO on the Structure and Piezoelectric Properties of the Alkaline Niobate-Based Lead-Free Ceramics

Recently, it was reported that the alkaline niobate-based (K,Na,Li)(Nb,Ta,Sb)O₃ (LF4) perovskite ceramics showed excellent piezoelectric properties and have been regarded as a new candidate of lead-free piezoelectric materials. However, the effects of additives on the piezoelectric property of LF4 have not been studied intensively so far. In this study, the effect of CuO addition to the LF4 was investigated. The sample showed a tetragonal phase at room temperature and also a second phase with low melt point. With 0.05 wt% CuO added, the Cu²⁺ firstly incorporated into the A site, while higher amounts of Cu²⁺ substituted B-site ions. The CuO-doping changed the LF4 to "hard" piezoelectric ceramics with improvement of mechanical quality factor from 26 to 137 but the piezoelectric d ₃₁ constant and the electromechanical coupling constant reduced drastically at the same time.     

Genes and Gene Networks Involved in Sodium Fluoride-Elicited Cell Death Accompanying Endoplasmic Reticulum Stress in Oral Epithelial Cells

Here, to understand the molecular mechanisms underlying cell death induced by sodium fluoride (NaF), we analyzed gene expression patterns in rat oral epithelial ROE2 cells exposed to NaF using global-scale microarrays and bioinformatics tools. A relatively high concentration of NaF (2 mM) induced cell death concomitant with decreases in mitochondrial membrane potential, chromatin condensation and caspase-3 activation. Using 980 probe sets, we identified 432 up-regulated and 548 down-regulated genes, that were differentially expressed by >2.5-fold in the cells treated with 2 mM of NaF and categorized them into 4 groups by K-means clustering. Ingenuity^® pathway analysis revealed several gene networks from gene clusters. The gene networks Up-I and Up-II included many up-regulated genes that were mainly associated with the biological function of induction or prevention of cell death, respectively, such as Atf3, Ddit3 and Fos (for Up-I) and Atf4 and Hspa5 (for Up-II). Interestingly, knockdown of Ddit3 and Hspa5 significantly increased and decreased the number of viable cells, respectively. Moreover, several endoplasmic reticulum (ER) stress-related genes including, Ddit3, Atf4 and Hapa5, were observed in these gene networks. These findings will provide further insight into the molecular mechanisms of NaF-induced cell death accompanying ER stress in oral epithelial cells.