Excellent properties of 0.15 micrometer ferroelectric PZT capacitor with SRO electrodes for future Gbit-scale ferams

Abstract

Excellent ferroelectric properties of PZT capacitors with 0.15μ m lateral dimension were obtained for the first time using SrRuO₃ electrode technology. The switching charge of the capacitor was not degraded even for the 0.15 μ m capacitor. The ferroelectric properties such as saturation, fatigue, and imprint characteristics were similar for the capacitors with 12 μ m to 0.15 μ m dimensions. We demonstrated that the SrRuO₃ electrode technology could be used for the future Gbit-scale FeRAMs. An apparent increase in switching charge was also observed with decrease in capacitor size. The ferro-film around the top electrode may contribute to the increase of switching charge.     

Novel decaffeination of green tea using a special picking method and shortening of the rolling process

We have recently succeeded in manufacturing low-caffeine tea (LCT) by employing a special picking method in the 3rd leaf period and shortening the leaf-rolling process. In the present study, the effect of this special method on the content of other physiologically active substances, such as catechins, theanine, and vitamin C, as well as the mechanism of reduction of caffeine content in the LCT were investigated using capillary electrophoresis. By comparing the various components of tea leaves at different picking periods with or without shortening of the rolling process, it was found that the delayed leaf picking period and shortening of the rolling process used in the manufacture of LCT selectively reduced the caffeine content while retaining catechins, theanine, and vitamin C at a sufficient level. Therefore, our study demonstrated that this modified method may be useful in the manufacture of decaffeinated green tea.     

Proline accumulation in baker's yeast enhances high-sucrose stress tolerance and fermentation ability in sweet dough

During bread-making processes, yeast cells are exposed to various baking-associated stresses. High-sucrose concentrations exert severe osmotic stress that seriously damages cellular components by generation of reactive oxygen species (ROS). Previously, we found that the accumulation of proline conferred freeze-thaw stress tolerance and the baker's yeast strain that accumulated proline retained higher-level fermentation abilities in frozen doughs than the wild-type strain. In this study, we constructed self-cloning diploid baker's yeast strains that accumulate proline. These resultant strains showed higher cell viability and lower intracellular oxidation levels than that observed in the wild-type strain under high-sucrose stress condition. Proline accumulation also enhanced the fermentation ability in high-sucrose-containing dough. These results demonstrate the usefulness of proline-accumulating baker's yeast for sweet dough baking.     

Pulse switching characteristics of MAGTs for pulsed power applications

For pulsed power systems such as lasers and accelerators, semiconductor switches with their longer service life have actively been developed as replacements for thyratrons. The MOS-driven thyristors are suitable for pulsed power applications because they have high-power handling and fast turn-on capabilities. The MOS-assisted gate-triggered thyristor (MAGT), designed especially for pulsed power, is a promising candidate in this field. This paper presents the results of an investigation into the performance of MAGTs. Using a pulse-forming network (PEN), the pulse-switching characteristics and the dynamic resistance characteristics during the current flow are investigated. A maximum current density of 21.8 kA/cm² and di/dt of 106 kA/μs/cm² with 1550-V anode voltage on a single-shot basis were obtained. Furthermore, a life test with 10⁹ shots at a high repetition rate showed no degradation in the observed characteristics. Based on these experimental results, a carrier flow model of MAGT during turn-on process is proposed and the turn-on mechanism is considered.     

Decentralized system identification for electric power system

Research on decentralized control of an electric power system is important for stabilizing control problems. In particular, since an electric power system is a large-scale nonlinear control system, decentralized (not divided) systems with cooperation should be constructed. This paper presents ways to construct decentralized systems for an electric power system. In section 2, swing data of a three-machine model system are obtained, in section 3, coefficient parameters of the model equation based on one-machine infinite-bus system with AVR and GOV are estimated by the least square method. In section 4, the equivalence calculated using estimated values is discussed, and the effect of conditions on fault is considered. Finally, section 5 is devoted to summarizing results of decentralized system identification.     

Mechanical strength of fusion-spliced optical fibres

Mechanical strengths of optical fibres heated under different electric-discharge conditions have been systematically examined. Exclusion of fibre surface contaminations and making heating duration as short as possible are important for prevention of strength deterioration.     

A flexible OLED display with an OTFT backplane made by scalable manufacturing process

Abstract— A full‐color top‐emission AMOLED display driven by an organic TFT backplane manufactured using a scalable, lift‐off‐free, and shadow‐mask‐free process has been developed. It was shown that cost‐efficient copper can be used for S/D electrodes. The display has shown no significant degradation over a storage life of more than 10 months and operation over 25 hours during which the display is bent over 10,000 times.