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Rationale: Recently, metabolome analysis has been applied to a variety of research fields, but differences between batches or facilities can cause discrepancies in the results of such analyses. To resolve these issues using comprehensive metabolome analysis, in which it is difficult to perform quantitative analyses of all detected metabolites, internal standard compounds are used to obtain relative metabolite levels. This study investigated gas chromatography/mass spectrometry–based plasma metabolome analysis methods that are superior to relative quantification using internal standard compounds. Methods: In experiment I, four analyses were performed under different analytical conditions at one facility, and then the data from the four analyses were compared. In experiment II, the same samples were analyzed at three facilities, and then the data from the three facilities were compared. Results: Regarding the relative values obtained through comparisons with the internal standard compound, differences in the analytical results were observed among the four analytical conditions in experiment I and among the three facilities in experiment II, and the differences observed among the three facilities (experiment II) were larger. When correction was performed using plasma as a quality control, which is the procedure suggested in this study, these differences were markedly ameliorated. Conclusion: The suggested procedure involves the analysis of a plasma standard as a quality control for each batch and the calculation of relative target plasma to quality‐control plasma values for each metabolite. This is an easy and low‐cost method and could be readily employed by researchers during comprehensive plasma metabolome analysis. [ABSTRACT FROM AUTHOR]

A gyrotron with an axis-encircling electron beam is capable of high-frequency operation, because the high-beam efficiency is kept even at high harmonics of the electron cyclotron frequency. We have designed and constructed such a gyrotron with a permanent magnet. The gyrotron has already operated successfully at the third, fourth, and fifth harmonics. The frequencies are 89.3, 112.7, and 138 GHz, respectively, and the corresponding cavity modes are T[E.sub.311], T[E.sub.411], and T[E.sub.511]. The permanent magnet system is quite novel and consists of many magnet elements made of NbFeB and additional coils for controlling the field intensities in the cavity and electron gun regions. The magnetic field in the cavity region can be varied from 0.97 to 1.18 T. At the magnetic field intensities, the output powers at the third and the fourth harmonies are 1.7 and 0.5 kW, respectively. The gyrotron is pulsed, the pulse length is 1 ms and the repetition frequency is 1 Hz. The beam energy is 40 kV and the beam current is 1.2-1.3 A. Beam efficiencies and emission patterns have also been measured. In this paper, the experimental results of the gyrotron are described and compared with computer simulations. Index Terms--Axis-encircling electron beam, gyrotron, high harmonic, permanent magnet.