Showing papers by "Sungkyunkwan University published in 1990"

Simultaneous determination of cefoxitin, cefuroxime, cephalexin and cephaloridine in plasma using HPLC and a column-switching technique

Abstract: A new high performance liquid chromatographic method was developed using a column-switching technique for the simultaneous determination of cephalexin, cefuroxime, cefoxitin and cephaloridine in plasma. The plasma samples were injected onto a precolumn packed with Corasil RP C18 (37–50 μm) after simple dilution with an internal standard solution in 0.01 M acetate buffer (pH 3.5). Polar plasma components were washed out using 0.01 M acetate buffer (pH 3.5). After valve switching, the concentrated drugs were desorbed in back-flush mode and separated on a Partisil ODS-3 column using acetonitrile in 0.02 M acetate buffer (pH 4.3) (15∶85, v/v) as the mobile phase. The method showed excellent precision with good sensitivity and speed with a detection limit of 0.5 μg/ml. The total analysis time per sample was less than 25 min, and the mean coefficients of variation for intra- and inter-assay were both less than 4.9 %.

Negative thermopower of YbBa 2 Cu 3 O 7-y

Abstract: We have measured the thermopower of R${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{y}}$ for R=Yb, Er, Y, Dy, and Gd as a function of temperature with further details on the Yb compound. We find that the Yb compound has a negative thermopower at all temperatures above ${\mathit{T}}_{\mathit{c}}$ unlike the other compounds, whereas its temperature dependence is similar to that of the others. We also find that as the oxygen deficiency increases, the thermopower of ${\mathrm{YbBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{y}}$ increases and becomes positive, while the whole shape of the thermopower-versus-temperature curve remains nearly unchanged. The observed insensitivity of the thermopower-versus-temperature profile to the sign of the thermopower or to the carrier concentration indicates that the electronic structure of the 1:2:3 compounds cannot be adequately explained within a single-conduction-band framework.

CMAC toward intelligent robot: motion and calibration

Abstract: The cerebellar model arithmetic controller (CMAC), a kind of neuro-net based adaptive control function generator, has been successfully applied to the problems of inverse kinematic motion of two DOF manipulator and direct inverse calibration of three and six DOF PUMA 560 robots. Since CMAC-net autonomously maps and generalizes a desired system function via learning, CMAC allows no knowledge in modeling a system and other error sources. The mapping structure, learning aspects with algorithms, and the convergence of CMAC net are also briefly stated. >