Interface reactions between SiO2-PbO glass and Ni-Zn ferrite

The interface reactions between SiO₂-PbO melt and Ni-Zn ferrite were studied using electron probe microanalysis and X-ray diffraction. The mechanisms of interface reaction were investigated in relation to the glass-forming region. No intermediate layers were produced at the interface between SiO₂-PbO glass and Ni-Zn ferrite because of the small amount of dissolution of Ni²⁺ ion from the ferrite. A model of the interface reaction mechanism between SiO₂-PbO melt and Ni-Zn ferrite is proposed.     

Simulation of the optical illusions using a spatial filter

Emphasis is placed on finding an example of the spatial filter being successful in simulating some of the well-known optical illusions. A modeling of the visual system has been made in the first stage of this work referring to the already surveyed spatial frequency responses of the human visual system and the other related characteristics. Design of the spatial filter has played a key role in the modeling stated here, because it mainly governs the performance of the proposed model used for simulating optical illusions.Four kinds of the famous illusion patterns have been tested to specify the spatial filter suitable for our simulation and successful examples of the simulated fields interpreting the illusions have been presented.     

Growth control of carbon nanotubes by plasma-enhanced chemical vapor deposition and reactive ion etching

A novel process for growth of carbon nanotubes using plasma processes is reported. This process consists of formation of nanotips on substrate and growth of carbon nanotubes on it. The formation of the nanotips, which were formed under an intention to control formation of catalyst nanoparticles, was carried out on substrates by reactive ion etching. After the nanotips formation, the carbon nanotubes were grown on the substrate by plasma-enhanced chemical vapor deposition. Our results showed that the introduction of the nanotips on surface gave lower density and smaller diameter growth of carbon nanotubes than those without the structure.     

Total Synthesis and Structural Revision of Kasumigamide,and Identification of a New Analogue

Kasumigamide is an antialgal hybrid peptide–polyketide isolated from the freshwater cyanobacterium Microcystis aeruginosa (NIES-87). The biosynthetic gene cluster was identified from not only the cyanobacterium but also Candidatus “Entotheonella”, associated with the Japanese marine sponge Discodermia calyx. Therefore, kasumigamide is considered to play a key role in microbial ecology, regardless of the terrestrial and marine habitats. We now report synthetic studies on this intriguing natural product that have led to a structural revision and the first total synthesis. During this study, a new analogue, deoxykasumigamide, was also isolated and structurally validated. This study confirmed the presence of the unusual pathway in the biosynthesis of a hybrid peptide–polyketide natural product.     

Comparison of performance between benzoindoline and indoline dyes in zinc oxide dye-sensitized solar cell

The cell performance of novel benzoindoline dyes on zinc oxide prepared by template cathode electro-deposition method was compared with that of known indoline dyes. Among cyanoacrylic, single and double rhodanine acetic acid derivatives, the cyanoacrylic benzoindoline dye showed better performance than the indoline dye (D131) due to larger J_sc value which comes from its positive E_ox level and bathochromic UV-vis absorption band.     

Bioactivities of nostocine a produced by a freshwater cyanobacterium Nostoc spongiaeforme TISTR 8169

A freshwater cyanobacterium, Nostoc spongiaeforme TISTR 8169, synthesizes and releases a violet pigment, nostocine A, into medium. We examined the bioactivity of nostocine A to several model organisms breeding with N. spongiaeforme in the natural environment. To microalgae, nostocine A exhibited growth inhibitory activity comparable to paraquat, and the activity tended to be stronger to green algae than to cyanobacteria. Nostocine A also exhibited strong inhibitory activity to the root elongation of barnyard grass, strong antifeedant activity to cotton ballworm, and acute toxicity to mice resulting in its classification as a dangerous poison. The results suggest that nostocine A may act as a toxin or an allelochemical to breeding organisms in nature. In a laboratory culture of N. spongiaeforme, the production of nostocine A was enhanced at higher temperature, 30 degrees C, and more intense light, 30 W/m2, than the basal conditions, 25 degrees C and 10 W/m2. Cultivation of cells with H2O2 at 1 or 2 mM also enhanced the production of nostocine A, indicating that nostocine A may be synthesized and released when the cells are exposed to oxidative stress, possibly occurring at higher temperature and more intense light. LC-MS and electron spin resonance analyses revealed that nostocine A, reduced previously by NaBH4, immediately recovered to its original form upon exposure to air and the generation of superoxide radical anions occurred at this re-oxidation step. These results suggest that the adverse effects of nostocine A on various organisms may be related to the function of nostocine A in generating toxic reactive oxygen species, which occurs in the cells of target organisms.     

Polymerization properties of polyamide in bottom‐up prepared polyamide‐calcium carbonate composites

Polyamide/calcium carbonate composites (CaCO₃) were prepared by bottom‐up process, using a precipitated CaCO₃ with polyamide monomers followed by the polymerization of the polyamide. The composites before and after the polymerization treatment were studied by gel permeation chromatography, differential scanning calorimetry, X‐ray powder diffraction, and attenuated total reflectance—Fourier transform infrared spectroscopy. A van der Waals interaction between monomer molecules and CaCO₃ surface, which was suggested by the blue shift in IR absorption band of NH₂ and CH₂, restricted the molecular motions of monomers on the CaCO₃ surfaces to inhibit the proceeding of polymerization reactions. A resembled blue shift was also observed in the polyamide/CaCO₃ composites. Besides the hydrophilic; hydrogen bonding and ionic, interactions, the van der Waals interaction should not be ignored and had a significant effect on the polymerization reactions. POLYM. COMPOS., 35:1132–1139, 2014. © 2013 Society of Plastics Engineers     

Depletion-layer Dielectric Properties of Positive Temperature Coefficient of Resistance Barium Titanate

For pure and impurity-added positive temperature coefficient of resistance (PTCR) barium titanate ceramic samples, a −11°C shift of the Curie point at the grain-boundary/depletion-layer region was observed. This result is obtained by fitting the PTCR grain-boundary resistance and capacitance data to a theory which combines a double-depletion-layer model with the Devonshire thermodynamic theory of barium titanate. The parameters used in the fitting are obtained from independent experiments. The shift of the Curie point is believed to result from the grain-boundary clamp ing effect near the cubic-tetragonal phase transition point.     

Analysis of magnetic saturation in a salient‐pole synchronous machine after sudden three‐phase short circuit

In order to evaluate magnetic saturation under subtransient and transient states of a large‐sized salient‐pole synchronous machine, the currents and leakage inductances after sudden three‐phase short circuits are analyzed by a two‐dimensional nonlinear transient finite element method (FEM). The currents are calculated both by direct and indirect methods. The direct method uses the FEM and considers fluctuation of the magnetic saturation after the short circuit. The indirect method solves Park's differential equations without fluctuation. Results of the direct method agree well with measurements. When the preshort voltage is large, fluctuation of the leakage inductances after the short is large and it greatly affects values of the short‐circuit currents. As the preshort voltage becomes large, the damper leakage inductances saturate at first, then the field leakage inductances, and finally the armature leakage inductances saturate. Although the indirect method considers saturation under the preshort condition, it gives inaccurate results and they are nearly the same as the results by the linear FEM. In general, it is thought that saturation of the leakage flux should be considered when subtransient conditions with large disturbance are analyzed. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 46–55, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10240