Search

Abstract Background Lycopene epsilon-cyclase (ε-LCY) is a key enzyme in the carotenoid biosynthetic pathway (CBP) of higher plants. In previous work, we cloned two Ntε-LCY genes from allotetraploid tobacco (Nicotiana tabacum), Ntε-LCY2 and Ntε-LCY1, and demonstrated the overall effect of Ntε-LCY genes on carotenoid biosynthesis and stress resistance. However, their genetic and functional characteristics require further research in polyploid plants. Results Here, we used CRISPR/Cas9 to obtain Ntε-LCY2 and Ntε-LCY1 mutants in allotetraploid N.tabacum K326. Ntε-LCY2 and Ntε-LCY1 had similar promoter cis-acting elements, including light-responsive elements. The Ntε-LCY genes were expressed in roots, stems, leaves, flowers, and young fruit, and their highest expression levels were found in leaves. Ntε-LCY2 and Ntε-LCY1 genes responded differently to normal light and high light stress. Both the Ntε-LCY2 and the Ntε-LCY1 mutants had a more rapid leaf growth rate, especially ntε-lcy2-1. The expression levels of CBP genes were increased in the ntε-lcy mutants, and their total carotenoid content was higher. Under both normal light and high light stress, the ntε-lcy mutants had higher photosynthetic capacities and heat dissipation levels than the wild type, and this was especially true of ntε-lcy2-1. The reactive oxygen species content was lower in leaves of the ntε-lcy mutants. Conclusion In summary, the expression patterns and biological functions of the Ntε-LCY genes Ntε-LCY1 and Ntε-LCY2 differed in several respects. The mutation of Ntε-LCY2 was associated with a greater increase in the content of chlorophyll and various carotenoid components, and it enhanced the stress resistance of tobacco plants under high light.

The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions.

The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions. [ABSTRACT FROM AUTHOR]

A reduced graphene oxide-zinc phthalocyanine (RGO-ZnPc) hybrid material with good dispersibility has been prepared by covalent functionalization method, based on the initial covalent linkage of ZnPc to GO and subsequent in situ reduction of GO moiety to RGO during mild thermal treatment in DMF solvent. The microscopic structure, morphology and photophysical properties of resultant RGO-ZnPc hybrid are characterized. The nonlinear optical (NLO) properties of the RGO-ZnPc hybrid are also investigated using the Z-scan technique at 532nm with 4ns laser pulses. The results show that the efficient functionalization and reduction of GO make RGO-ZnPc hybrid possess much larger NLO properties and optical limiting performance than those of individual GO, ZnPc and the GO-ZnPc hybrid. It can be ascribed to a combination of different NLO absorption mechanisms for RGO-ZnPc hybrid, including two-photon absorption originating from the sp³ domains, saturable absorption from the sp² carbon clusters and excited state absorption from numerous localized sp² configurations in RGO moiety, reverse saturable absorption arising from ZnPc moiety and the contribution of efficient photo-induced electron transfer or energy transfer process between ZnPc and RGO. [ABSTRACT FROM AUTHOR]

The effect of hydrofluoric acid (HFA) on the upgrading and structure of oil shale from Yilan county, Heilongjiang province, China was investigated by the ultrasonic treatment of the shale in a mild water bath. The oil shale samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron (SE) microscopies, as well as Fourier transform infrared (FTIR) spectroscopy, and densimetry. The results of the study indicate that the HFA-based ultrasonic treatment exhibited a better performance in upgrading oil shale than the ordinary mechanical stirring method. It was also found that the concentration of HFA significantly influenced upgrading performance and the separation degree of inorganic minerals. The kerogen content in oil shale increased with increasing concentration of HFA. The total content of C, H, O and N in oil shale reached 98.2% when 40% HFA was used. Oil shale is composed mainly of a chainlike cyclic saturated organic material called kerogen, and inorganic minerals such as quartz, kaolinite, illite, siderite and pyrite. These materials integrate into a smooth lithified sandwich by the hydrogen bond and intermolecular forces. Via the ultrasonic treatment under mild conditions, kaolinite and siderite can be removed from oil shale with the use of a weak HFA, while a stronger HFA is needed to leach illite and quartz. Then kerogen with a loose porous structure is obtained. [ABSTRACT FROM AUTHOR]