Nine novel oxylipin metabolites together with several known ones were isolated from the brown alga Eisenia bicyclis. Five (1-5) of them are ecklonialactone derivatives containing a chlorine or an iodine atom, and two (6 and 7) are cymathere type oxylipins with a lactone ring or a chlorine atom. The structures of these oxylipin metabolites were confirmed by NMR and mass spectroscopy and compared with spectral data in the literature. The postulated biosynthetic pathway of these metabolites is discussed.

This paper describes a three-phase current source GTO (gate turn-off thyristor) rectifier with high power factor, low line current distortion, and a simple main circuit. It adopts new PWM (pulse width modulation) control techniques obtained by analyzing the PWM patterns of three-phase current source rectifierdinverters and a new method of generating such patterns. I n addition, by executing optimum setup of the circuit constants, we have reduced GTO switching frequency from about 2 kHz of the conventional frequency to 500 Hz. This rectifier is suitable for large power conversion, because it can reduce GTO switching loss and its snubber loss. . INTRODUCTIONRecently current source GTO PWM rectifiers with high power factor and low line current distortion have been developedtl)-(41. But each GTO in these rectifiers has been switched at the high frequency of over 2 kllz, or the main circuit has been complex. So it is difficult to apply them to large power conversion over several hundred kW, because switching and snubber loss is too large, or their cost is excessive. To solve the problem, we have developed a rectifier with a simple main circuit, which operates a t 500Hz of GTO switching frequency, by adopting new PWM control techniques.This paper describes the configuration, the PWM control method for reducing GTO switching frequency to 500Hz and the method of circuit analysis. Paticularly, as the PWM control method, the analyzed result of PWM patterns of three-phase current source rectifiexdinverters, the control principle and the control circuit are introduced. Results of experiments and the circuit analysis, and the results of t h e study on circuit constants a r e also introduced.

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This paper describes a method for selecting pulse-width modulation (PWM) patterns and a method for designing low-pass filters in large-capacity current-source PWM converters, to suppress higher harmonics flowing into the power supply. A test carried out on a 500kVA PWM converter, employing the methods proposed by this paper, verified that these methods substantially decrease higher harmonics flowing into the power supply. The test also showed highly efficient converter characteristics with a power factor of the supply equaling almost 1.0.