Isao Takenaka

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Proton release by flash excitations was measured with right-side-out vesicles prepared from Rhodopseudomonas sphaeroides by lysozyme-EDTA treatment followed by hypotonic treatment. Absorbance change at 586 nm in the presence of bromcresol purple was measured to monitor the pH change. In the presence of horse heart cytochrome c, which catalyzes the electron(More)
An L/S-band high-power and low-distortion AlGaAs/GaAs HFET amplifier has been developed. The amplifier employed two pairs of pre-matched GaAs chips mounted on a single package and the total output-power was combined in push-pull configuration with a microstrip balun circuit. The developed amplifier demonstrated state-of-the-art performance of 140 W(More)
This paper presents the improvement techniques of intermodulation-distortion asymmetries with wide carrier-spacing signals in L/S-band high power amplifiers. We proposed a novel circuit technique to directly connect LC series resonant circuits to the gate and drain electrodes of the transistor die in a package for baseband terminations with a wide frequency(More)
An L/S-band 330-W distortion-cancelled Doherty GaAs field-effect transistor (FET) amplifier has been successfully developed optimizing the main and peak amplifiers load impedance shift. The amplifier employed a pair of 28-V operation 150-W GaAs heterojunction FETs. It demonstrated low third-order intermodulation of -37 dBc with a drain efficiency of 42% at(More)
We have successfully developed high-efficiency and high-power microwave amplifiers using a GaN field-effect transistor (FET) on a low-resistivity (LR) Si substrate for the first time. By introducing the LR Si substrate whose resistivity is less sensitive over temperature, the efficiency characteristics in high-temperature operation were significantly(More)
On encountering a potential host, egg parasitoids examine its surface with antennae while walking over it. They begin to probe or penetrate the host chorion with their ovipositor only after antennal examination. Many parasitoids assess size, age, and previous parasitism for host profitability (Godfray, 1994). Host recognition by egg parasitoids is dependent(More)
We have successfully developed broadband low distortion cable television (CATV) power amplifier with AlGaN/GaN hetero-structure field-effect transistor (HFET) capable of high voltage operation for high output power. To realize low distortion characteristics required for modern CATV system, we investigated low distortion cascode configuration composed of(More)
We designed a species-specific primer pair for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). In polymerase chain reaction (PCR), these primers amplified a fragment (118 bp) of the internal transcribed spacer 1 region of the ribosomal RNA gene of the target species but not those of any of the tested species of Lepidoptera (except H. armigera),(More)
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