Digital input filters for measurement,control and protection of electric power systems

Power system control and protection equipment has required higher sensitivity and operational reliability than conventional one. Studies of digital signal processing suitable for electric power systems fulfill this objective using fast sampling and digital filtering by a 32-bit floating point DSP (Digital Signal Processor). The sampling rate of 3 kHz is carefully selected in order to separate the power spectrums of the A-D conversion output errors from the signal bandwidth. The new 12-bit A-D conversion unit equipped with a recursive-type digital filter achieved the equivalent high resolution of 14-bit conversion. This paper describes the design concept and the characteristics showing applications to current differential relays, distance relays and power system controllers.     

Stability of Singlet- and Triplet-Charged Excitons in CdTe/CdMgTe Two-Dimensional Electron Systems Around ν = 1

Magnetoluminescence experiments in CdTe/CdMgTe single-quantum well with dense two-dimensional electron gases are performed at high magnetic fields up to 35 T. A broad photoluminescence peak, which originates in the Fermi edge singularity, evolves into singlet-charged excitons under the magnetic field in both ⁺ and ^– polarization. A triplet-charged exciton peak, however, appears only in the ^– polarization, and the intensity of the triplet peak becomes intense above the magnetic field where the singlet peak of the ⁺ polarization crosses the triplet peak. The crossing magnetic field is consistent with the recent theoretical calculation of the magnetic field dependence of the charged excitons by Redliski and Kossut, confirming that the nature of the PL peaks around = 1 can be explained from the viewpoint of the charged excitonic transitions even for the dense two-dimensional electron systems.     

Stability of Singlet- and Triplet-Charged Excitons in CdTe/CdMgTe Two-Dimensional Electron Systems Around ν = 1

Magnetoluminescence experiments in CdTe/CdMgTe single-quantum well with dense two-dimensional electron gases are performed at high magnetic fields up to 35 T. A broad photoluminescence peak, which originates in the Fermi edge singularity, evolves into singlet-charged excitons under the magnetic field in both ⁺ and ^– polarization. A triplet-charged exciton peak, however, appears only in the ^– polarization, and the intensity of the triplet peak becomes intense above the magnetic field where the singlet peak of the ⁺ polarization crosses the triplet peak. The crossing magnetic field is consistent with the recent theoretical calculation of the magnetic field dependence of the charged excitons by Redliski and Kossut, confirming that the nature of the PL peaks around = 1 can be explained from the viewpoint of the charged excitonic transitions even for the dense two-dimensional electron systems.     

Stereoisomeric identification of norephedrine derived from methamphetamine or amphetamine: urinalysis results of 33 methamphetamine abusers and 1 amphetamine abuser in Japan

Stereoisomeric identification of norephedrine (NE) derived from methamphetamine (MA) or amphetamine (AM) was investigated by SIM-GC/MS assay using the urine of 33 MA abusers and 1 AM abuser. The assay simultaneously identified TFA-derivatized MA and AM metabolites, including AM, p-hydroxyl-MA (p-HMA), and p-hydroxyl-AM (p-HAM). The analysis lasted approximately 43 min, with a signal-to-noise ratio of >or=3 and a detection limit of 50 ng/mL. Among 12 urine samples from different subjects, only the S (+) form of MA and its metabolites (AM, p-HMA, p-HAM) was detected, however, a (1R,2S)-(-)-NE stereoisomer was also identified. Among the urine samples of two subjects, only the R (-) form of MA and its metabolites (AM, p-HMA, p-HAM) was detected, while NE was not detected. Following urinalysis of urine obtained from 19 MA abusers and 1 AM abuser, only the (1R,2S)-(-)-NE stereoisomer was identified, while unmetabolized MA, AM, and their metabolites (p-HMA, p-HAM), showed stereoselective metabolism. Although (1R,2S)-(-)-ephedrine (EP) alone was found in the urine of 1 (S)-(+)-MA user and 1 (S)-(+)- and (R)-(-)-MA user among 33 MA users, it was not present in the urine of the remaining 31 subjects. Therefore, (1R,2S)-(-)-NE was likely not of (1R,2S)-(-)-EP origin and was most likely from (S)-(+)-AM of the MA metabolite. The production ratio of (1R,2S)-(-)-NE to (S)-(+)-AM ranged from 0.01 to 0.25 in MA abusers and was 0.12 in AM abusers.     

Preparation and Enzymatic Degradation of Porous Crosslinked Polylactides of Biomass Origin

To understand the enzymatic degradation behavior of crosslinked polylactide (PLA), the preparation and enzymatic degradation of both thermoplastic (linear) and crosslinked PLAs that have pore structures with different dimensions were carried out. The porous structures of the linear PLA samples were of micro and nanoporous nature, and prepared by batch foaming with supercritical CO₂ and compared with the porous structures of crosslinked PLA (Lait-X) created by the salt leaching method. The surface and cross-sectional morphologies of the porous structures were investigated by using scanning electron microscopy. The morphological analysis of porous Lait-X showed a rapid loss of physical features within 120 h of exposure to proteinase-K enzymatic degradation at 37 °C. Due to the higher affinity for water, enhanced enzymatic activity as compared to the linear PLA porous structures in the micro and nanoporous range was observed.     

Transport of carnitine and acetylcarnitine by carnitine/organic cation transporter (OCTN) 2 and OCTN3 into epididymal spermatozoa

Carnitine and acetylcarnitine are important for the acquisition of motility and maturation of spermatozoa in the epididymis. In this study, we examined the involvement of carnitine/organic cation transporter (OCTN) in carnitine and acetylcarnitine transport in epididymal spermatozoa of mice. Uptake of both compounds by epididymal spermatozoa was time-dependent and partially Na(+)-dependent. Kinetic analyses revealed the presence of a high-affinity transport system in the spermatozoa, with K(m) values of 23.6 and 6.57 muM for carnitine and acetylcarnitine respectively in the presence of Na(+). Expression of OCTN2 and OCTN3 in epididymal spermatozoa was confirmed by immunofluorescence analysis. The involvement of these two transporters in carnitine and acetylcarnitine transport was supported by a selective inhibition study. We conclude that both Na(+)-dependent and -independent carnitine transporters, OCTN2 and OCTN3, mediate the supply of carnitine and acetylcarnitine to epididymal spermatozoa in mice.