A SPECIFIC QUALITATIVE DETECTION METHOD FOR PEANUT (ARACHIS HYPOGAEA) IN FOODS USING POLYMERASE CHAIN REACTION

A qualitative method for detection of peanuts in foods using polymerase chain reaction was developed. A universal primer pair CP 03‐5′/CP 03‐3′ was designed to confirm the validity of the DNAs for PCR. The plant‐specific amplified fragments were detected from 13 kinds of plants using the universal primer pair. In addition, for the specific detection of peanuts with high sensitivity, the primer pair agg 04‐5′/agg 05‐3′ was designed to detect the gene encoding the peanut agglutinin precursor. The primer pair specifically generates a 95‐bp amplified fragment from peanut genomic DNA. Five hundred femto grams of peanut genomic DNA can be detected using the established method. The same qualitative results were obtained from both model processed and nonprocessed food samples containing 0.001, 0.01 and 0.1% of peanut. Moreover, it was shown that the trace amount of peanut in the commercial food products could be qualitatively detected using this method. The reproducibility and applicability of the proposed methods were verified in a six‐laboratory collaborative study.     

Improved Modified Switching Transient Pulse Width Modulation (MT‐PWM) Method Applied to H‐Bridge Type Step‐Down Converter

The authors have devised a new method to decrease high‐frequency harmonics in a specific frequency band by modifying the switching transient slope. In previous studies, there were several problems in applying modified transient pulse width modulation (MT‐PWM) to actual converters. In this paper, three problems are solved using an improved MT‐PWM method. First, the MT‐PWM signal was obtained using a trial‐and‐error approach that involved complex computation procedures in the previous studies. In this paper, a new calculation procedure for obtaining the MT‐PWM waveform using a simple calculation is proposed. Second, a new controller (drain‐source voltage controller) based on voltage feedback is proposed in order to realize a modified switching transient to increase the stability of the switching operation. Third, the dependency of MT‐PWM on source voltage variation is investigated in order to implement MT‐PWM in an actual step‐down converter. From this result, the concept of a new type of controller with the source voltage variation taken into consideration is proposed. Finally, the authors attempted to apply MT‐PWM to an H‐bridge converter to expand the application of MT‐PWM. An H‐bridge converter with MT‐PWM for a dc motor drive is successfully operated in an experiment.     

Proposal of Series‐Parallel Continuously Regulated Chopper Suitable for Auxiliary Power Supply of Railway Vehicle

The conventional auxiliary power supply (APS) of a railway vehicle is directly connected to the catenary through the LC filter. Hence, the switching devices of the APS must have a high breakdown voltage to account for catenary voltage fluctuation. On the other hand, low‐voltage switching devices have better characteristics that are desirable for low‐loss and high‐frequency operation. Therefore, a step‐down converter is incorporated between the LC filter and inverter to adapt to catenary voltage fluctuations when using low‐voltage switching devices. This paper proposes the series‐parallel continuously regulated chopper as a novel step‐down converter. First, the fundamental operation characteristics and output voltage control method of the proposed chopper are introduced. The simulation and experimental results for the fundamental characteristics are then described; the simulation and experimental values were almost the same as the theoretical values. The proposed chopper controls the output voltage at the expected value without dramatic fluctuation regardless of the input voltage fluctuation. In addition, a resonance damping control for a constant power load is proposed. The operational characteristics were considered under different potential distributions or load conditions.     

Structural and electrical properties of antiferroelectric lead zirconate thin films prepared by reactive magnetron co-sputtering

The structural and electrical properties of antiferroelectric lead zirconate thin films were investigated. The films were prepared by a reactive magnetron co-sputtering method followed by rapid thermal annealing. The crystallized films showed (240) preferred orientation on platinum-coated silicon substrates. The lead content in the films was found to affect the crystallization temperatures, the preferred orientation, the film morphology and the electrical properties. In particular, the hysteresis behaviour is sensitive to the amount of lead. The electric field forced transformation from the antiferroelectric phase to the ferroelectric phase was very similar to that observed in single crystals at room temperature, with a maximum polarization value of 70 μC cm^-2. The average field required to excite the ferroelectric state and that for reversion to the antiferroelectric state were 290 kV cm^-1 and 180 kV cm^-1 respectively. The dielectric constant was 200 with an associated loss of 0.05 at 1 MHz. The Curie temperature was 248 °C at 1 kHz. The conduction mechanism of the films was similar to that observed for lead zirconate titanate films. This revised version was published online in November 2006 with corrections to the Cover Date.     

One role of titanium compound particles in aluminium nitride sintered body

Microstructure of titanium compound particle in polycrystalline aluminium nitride (AlN) has been investigated using micro-auger electron spectroscopy (μ-AES). AlN-0.5 wt% TiO2-1.5 wt% Y2O3-0.4 wt% CaO system was sintered at 1850°C in nitrogen atmosphere using a graphite furnace. The AES studies show that the composition of the titanium compound particle is titanium, aluminium, carbon, oxygen, nitrogen and calcium. On the other hand, no calcium is observed by AES in the AlN grains and grain boundary. It is found that one role of the titanium compound particle is to trap calcium included in polycrystalline AlN. This revised version was published online in November 2006 with corrections to the Cover Date.     

Flaking failures originating from microholes of bearings under rolling contact fatigue

Rolling contact fatigue tests were carried out using plates with microholes (diameter was about 100 μm and depth was about 140 μm) under three different loads (maximum values of Hertzian stress were about 3250, 3550 and 3840 MPa, respectively) and the surface cracks initiating from those holes were observed. It was found that there is a threshold value of maximum Hertzian stress whether surface cracks originate from microholes or not, and its value is between 3250 and 3550 MPa. However, flaking failures occurred even when the stress values were lower than the threshold value. In order to investigate the relation between the flaking failures and the cracks, sectional observations of the subsurface cracks were made before and after the surface layer separations. From these observations, it was found that the subsurface cracks caused the flaking failures even when the maximum value of Hertzian stress was lower than the threshold value of surface crack initiation.