1,507 research outputs found
Axion effects on gamma-ray spectral irregularities with AGN redshift uncertainty
We investigate the photon-ALP (axion-like particle) oscillation effect on TeV
gamma-ray spectral irregularities from the uncertain redshift active galactic
nuclei (AGN) VER J0521+211. The gamma-ray spectra are measured by the
collaborations Fermi-LAT and VERITAS with the three flux states in 2013 and
2014. We set the combined constraints on the ALP parameter ()
space with these states and test the extragalactic background light (EBL)
absorption effect on ALP constraints with the four redshift upper limit
scenarios of VER J0521+211. The 3 photon-ALP combined constraints set
by VER J0521+211 are roughly at for . We find no clear
connection between the redshift upper limit scenarios and the photon-ALP
constraints.Comment: 6 pages, 5 figure
Isolation of nematicidal constituents from essential oil of Kaempferia galanga L rhizome and their activity against Heterodera avenae Wollenweber
Purpose: To explore the nematicidal activities of the essential oil of Kaempferia galanga rhizomes and its isolated constituents against Heterodera avenae.Methods: Essential oil of K. galanga rhizomes was obtained by hydrodistillation and characterized by gas chromatography/mass spectrometric (GC/MS) analysis using HP-5MS column. Evaluation of nematicidal toxicity was performed against juveniles (J2) of H. avenae. The bioactive constituent compounds were isolated and identified from the oil based on bioactivity-directed fractionation.Results: Forty-one components were identified and the main components of the essential oil of K. galanga are as follows: ethyl-ρ-methoxy cinnamate (34.79 %), ethyl cinnamate (20.72%), 1,8-cineole (8.96 %), trans-cinnamaldehyde (7.03%) and borneol (5.64 %). The essential oil exhibited nematicidal activity against the cereal cyst nematode with an LC50 value of 91.78 μg/mL. Ethyl cinnamate, ethyl ρ-methoxy cinnamate and trans-cinnamaldehyde (median lethal concentration LC50 = 100.60 μg/ml, 83.04 μg/mL and 94.75 μg/mL, respectively) exhibited stronger nematicidal toxicity than borneol (LC50 = 734.89 μg/mL) and 1,8-cineole (LC50 = 921.21 μg/mL) against the cereal cyst nematode.Conclusion: The results indicate that the essential oil of K. galanga and its isolated constituents have a potential for development into natural nematicides for the control of cereal cyst nematodes.Keywords: Kaempferia galanga, Heterodera avenae, Nematicidal activity, Cereal cyst nematodes, Ethyl cinnamate, Ethyl ρ-methoxy cinnamate, Trans-cinnamaldehyd
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