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To investigate the effects of trace element selenium on aroma enhancement of tobacco leaves, foliar spraying experiments with selenium fertilizers at different concentrations, 0 (CK), 5.25 g⋅ha-1 (S0), 10.50 g⋅ha-1 (S1), 15.75 g⋅ha-1 (S2), 21.00 g⋅ha-1 (S3) and 26.25 g⋅ha-1 (S4), and the effects of selenium fertilizers on selenium content (mass fraction), petroleum ether extracts and volatile aroma substances in cured leaves were studied. The results showed that: 1) Selenium content in tobacco leaves of the control treatment was only about 0.15 mg ⋅ kg-1, and the selenium content was significantly increased by the selenium fertilizer with the highest content at about 2.49 mg ⋅ kg-1. 2) With increasing selenium fertilizer concentration, the petroleum ether extract content first increased and then decreased, reaching the highest level in leaves of S3 treatment. The petroleum ether extract content in the upper and middle leaves of S3 treatment increased by 25.71% and 44.56%, respectively compared to that of the control. 3) After the application of the selenium fertilizer, the total amount of aroma substances in tobacco leaves increased significantly, with S1 treatment being the highest for upper leaves and S2 being the highest for middle leaves, which increased by 25.88% and 10.82%, respectively compared to that of the control. 4) The VIP value obtained by PLS-DA was used to screen for differential markers of aroma substances in tobacco leaves from different stalk positions. Combined with cluster analysis, 15 common aroma differential markers were found in the upper and middle leaves. KEGG pathway enrichment analysis indicated that selenium was involved in the regulation of terpenoid synthesis and phenylpropanoid metabolism to enhance the tobacco aroma substances. 5) Correlation analysis results showed that selenium content in tobacco leaves was significantly positively correlated with petroleum ether extract and phenylalanine degradation products. [ABSTRACT FROM AUTHOR]

Zirconium silicate (ZrSiO4) powders with different doping concentrations of Mn4+ were prepared by solid-state reactions. The effect on the photoluminescence properties of ZrSiO4: Mn4+ was studied. The structure of ZrSiO4: Mn4+ was analyzed by X-ray powder diffractometer (XRD). The result shows that the powder was completely synthesized at 1 400 T. The spectral properties of ZrSiO4 : Mn4+ powders at different doping concentrations were studied. The best luminescence performance was obtained at 0.3% Mn4+ doping concentration. In the excitation spectrum, the peak at 363 nm is caused by the superposition of the charge transfer band of O2--Mn4+ and the 4A2-4T1 energy level transition of the spin-allowed Mn4+, while the peak at 450 nm is caused by the 4A2-4T2 energy level transition of the Mn4+. The main emission peaking at 667 nm was due to the spin-forbidden transitions ²E-4A2 of Mn4+. The other peak located at 698 nm was caused by anti-stokes vibronic sidebands associated with the excited state ²E of Mn4+. The decay curves show that the lifetime of ZrSiO4: 0.1% Mn4+ powders is 0.204 1 ms. The results show that ZrSiO4: Mn4+ powders have good luminescent properties, they have the potential to be used in LED lighting industry. [ABSTRACT FROM AUTHOR]

Endocannabinoids and cannabinoid receptors are expressed in various central pain modulation regions. They maintain in dynamic changes in the expression level and distribution under different pathological and physiological conditions. These changes possess advantage as well as disadvantage. Exogenous administration of endocannabinoids exerts analgesic effect in different pain models, which is mainly mediated by the cannabinoid CB1 and CB2 receptors. Inhibition of enzymes for degrading endocannabinoids in different pain models also shows analgesic effect due to the increased local levels of endocannabinoids.