[A Time-Spatial Resolvable High Speed Spectrograph and Its Application on Spectrum Measurement of a Nanosecond Pulsed Underwater Spark Discharge].

Recently, the diagnosis of the characteristic of pulsed underwater electrical discharges plasma have received significant attention. The measurement of a time-spatial resolved spectrum emitted from a single discharge pulse is important for understanding the time-spatial evolution characteristics of plasma generated by a pulsed high-voltage discharge in water. In this paper, a high speed time-spatial resolvable spectrograph for measuring the emission spectrum of a single electrical discharge pulse was reported. The high speed time-spatial resolvable spectrograph has been constructed by combining an ultrahigh-speed frame camera system with monochromator. Software for the spectral analyzing was also developed. The performance of the spectrograph was tested by using a 632.8 nm He-Ne laser beam at a 1 200 g x mm(-1) grating. The pixel resolution for 632.8 nm spectra is 0.013 nm. The instrument broadening for 632.8 nm spectra is (0.150 ± 0.009)nm when the exposure.time of the camera is 20 ns and the width of entrance slit is 0.2 mm, and increases with increasing the slit width. The change of exposure time of the camera has no influence on the instrument broadening, ensuring the spectrograph in a steady performance while adjusting the exposure time of the camera. With the spectrograph, time-spatial resolved spectra emitted from a single discharge pulse of an underwater nanoseconds spark discharge were obtained. It provides good data for investigating the time-spatial evolution characteristics of the discharge plasma during a single discharge pulse. The spectrograph developed in this work provides a technical approach for studying the time-spatial evolution characteristic of, plasma generated by a single electrical discharge pulse.

Two new diterpenoids from Croton crassifolius.

Two new clerodane-type diterpenoids were isolated from the roots of Croton crassifolius Geisel. The structures of these compounds were elucidated as 9-[2-(2(5H)-furanone-4-yl)ethyl]-4,8,9-trimethyl-1,2,3,4,5,6,7,8-octahydronaphthalene-4-carboxylic acid (1) and methyl 9-[2-(2(5H)-furanone-4-yl)ethyl]-4,8,9-trimethyl-1,2,3,4,5,6,7,8-octahydronaphthalene-4-carboxylic ester (2) by spectroscopic methods.

[Chemical constituents of Berchemia lineate].

OBJECTIVE: To investigate the chemical constituents of the roots of Berchemia lineate as a medicinal plant of Yao nationality in China. METHODS: Compounds were isolated by various column chromatography and elucidated by physicochemical and spectral analysis. RESULTS: Nine compounds were isolated from the 95% ethanol extract of the roots of Berchemia lineate and their structures were identified as palmitic acid (1), octadecanoic acid (2), beta-sitosterol (3), stigmasterol (4), fernenol (5), chrysophanol (6), physcion (7), floribundiquinone D (8), 2-acetylphyscion(9) respectively. CONCLUSION: Compounds 1-4,7-9 are isolated from this plant for the first time,and compounds land 2 are firstly isolated from this genus.

[Diagnosis of the DC glow discharge plasma generated inside a metallic tube by optical emission spectroscopy].

Optical emission spectroscopy method was used to diagnose the normal dc glow discharge plasma generated inside a metallic tube. The active species in the plasma were identified. The electron excitation temperature in the plasma was determined by the Boltzmann plot method. The vibrational temperature of N2 molecules in the plasma was determined by analyzing the emission spectrum lines of the N2 second positive system (C3 IIu-->B 3IIg). The dependence of the electron excitation temperature and molecular vibrational temperature on the pressure was investigated. The experiment results show that in the Ar 60% + N2 40% glow discharge plasma at 20 Pa, the active species are the Ar atoms, Ar ions, second positive series of N transitions and theE first negative series of B (2)II2u-->X 2sigma g+; transitons; the electron excitation temperature is (15 270 +/- 250) K, and the vibrational temperature of N2 molecules is (3 290 +/- 100) K. The electron excitation temperature and molecular vibrational temperature decrease with increasing pressure. These results would give some valuable guide to the study on inner surface modification of metallic tubes.