Ultra-Long-Distance Hybrid BOTDA/Ф-OTDR.

In the distributed optical fiber sensing (DOFS) domain, simultaneous measurement of vibration and temperature/strain based on Rayleigh scattering and Brillouin scattering in fiber could have wide applications. However, there are certain challenges for the case of ultra-long sensing range, including the interplay of different scattering mechanisms, the interaction of two types of sensing signals, and the competition of pump power. In this paper, a hybrid DOFS system, which can simultaneously measure temperature/strain and vibration over 150 km, is elaborately designed via integrating the Brillouin optical time-domain analyzer (BOTDA) and phase-sensitive optical time-domain reflectometry (Ф-OTDR). Distributed Raman and Brillouin amplifications, frequency division multiplexing (FDM), wavelength division multiplexing (WDM), and time division multiplexing (TDM) are delicately fused to accommodate ultra-long-distance BOTDA and Ф-OTDR. Consequently, the sensing range of the hybrid system is 150.62 km, and the spatial resolution of BOTDA and Ф-OTDR are 9 m and 30 m, respectively. The measurement uncertainty of the BOTDA is ± 0.82 MHz. To the best of our knowledge, this is the first time that such hybrid DOFS is realized with a hundred-kilometer length scale.

[Study on the alkaloids constituents from Voacanga africana].

OBJECTIVE: To study the alkaloids of Voacanga africana. METHODS: The alkaloids were isolated by normal phase silica gel and Sephadex LH-20 column chromatography. Their structures were elucidated by analysis of spectroscopic data. RESULTS: Eight alkaloids were isolated and their structures were elucidated as voacangine(1), voacangine hydroxyindolenine(2), 19R-epi-voacristine(3), epi-ibogaine(4), vobasine(5), 19-epi-heyneanine(6), vobtusine(7) and voacamine(8). CONCLUSION: Compounds 2-4 and 6 are isolated from this plant for the first time.

[Studies on the chemical constituents of Ardisia tenera].

OBJECTIVE: To investigate the chemical constituents of Ardisia tenera Mez. METHODS: Compounds were isolated by normal phase silica gel, MCI GEL and Sephadex LH-20 gel column chromatography. Their structures were elucidated by analyses of spectroscopic data. RESULTS: Eight compounds were isolated, and their structures were elucidated as bauerenol (I), myristic acid (II), 11-phenyl-1-(2',6'-dihydroxy-4'-methoxy-phenyl)-undecan-1 -one (III), ardisinone A( IV), ardisinone B( V ), ardisinone C( VI), ardisinone F (VI), beta-sitosterol (VIII). CONCLUSION: All of these compounds are obtained from this plant for the first time.