The antioxidant capacity of 22 kinds of fruits was measured by the developed electron spin resonance (ESR) method based on Cu2+ sensor. Cu2+ is reduced to Cu+ by the antioxidants in the fruits, and the remaining Cu2+ ...
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The antioxidant capacity of 22 kinds of fruits was measured by the developed electron spin resonance (ESR) method based on Cu2+ sensor. Cu2+ is reduced to Cu+ by the antioxidants in the fruits, and the remaining Cu2+ was determined by ESR and UV-Vis spectroscopy. Cu2+ can give an ESR signal whereas Cu+ cannot, and the loss of the ESR signal was used to quantify the antioxidant capacity of various fruits. The results were shown as vitamin C equivalent antioxidant capacity (VCEAC). The VCEAC values obtained by ESR and UV-Vis methods ranged from 24.23 to 688.61 mg/100 g and from 24.12 to 677.79 mg/100 g, respectively. Cupric ion reducing antioxidant capacity (CUPRAC) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) methods were employed for comparison. Based on Pearson's correlation test, the results obtained by CUPRAC and DPPH methods were both significantly correlated with these obtained by the present method, which indicated that the novel method was reliable. Total phenolic content for all kinds of fruits was measured with the Folin-Ciocalteu reagent, and VCEAC values obtained by the ESR method were significantly correlated with total phenolic contents.
Nanoparticles stabilized Pickering emulsions have been widely applied in various fields. The size and morphology of nanoparticles are regarded as crucial factors for the emulsion stability. In this study, the dendriti...
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Nanoparticles stabilized Pickering emulsions have been widely applied in various fields. The size and morphology of nanoparticles are regarded as crucial factors for the emulsion stability. In this study, the dendritic mesoporous silica nanoparticles (DMSNs) and two kinds of hybrid dendritic mesoporous silica titanium nanoparticles (DMSTNs-0.01 and DMSTNs-0.03) have been successfully prepared and investigated for their potential application to stabilize Pickering emulsions. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV-Vis diffuse reflectance spectra are employed to confirm the successful fabrication of the nanoparticles. The stability of DMSNs and DMSTNs stabilized emulsions are systematically evaluated via the optical microscopy and static multiple light scattering. The DMSTNs-0.01 displays the greatest ability to stabilize emulsions. N-2 physisorption and atomic force microscopy demonstrate the stability of Pickering emulsions is closely related to the specific surface area and surface roughness of nanoparticles. Moreover, DMSTNs-0.01 stabilized O/W Pickering emulsions show satisfactory displacement performance (tertiary oil recovery of 14.05%) in core flooding experiments. Microscopic visualization tests further indicate the emulsions can effectively block the high permeability channels generated by initial water flooding to increase the flowing resistance and then cause the flow diversion of the repellent fluid to enlarge the sweep area.
We examined the correlations between winter aerosol optical depth (AOD) in North China (NC) and three synoptic-scale meteorological indices from 2001 to 2016, including the Siberian High intensity (SHI), East Asian Wi...
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We examined the correlations between winter aerosol optical depth (AOD) in North China (NC) and three synoptic-scale meteorological indices from 2001 to 2016, including the Siberian High intensity (SHI), East Asian Winter Monsoon intensity (EAWMI), and the Siberian High Position index (SHPI). To separate the influences from meteorology and emissions, NC AOD was detrended by subtracting a linear increasing trend from 2001 to 2013 and a decreasing trend from 2014 to 2016, in correspondence with reported changes in Chinese anthropogenic emissions during the same period. The SHPI explains 37% of the variability in the detrended NC AOD and 83% of the high SHPI winters correspond to high AOD. By contrast, the SHI and EAWMI show little correlation with the observed AOD variability. To project the SHPI in the future climate, we used the ensemble of six global circulation models (GCMs) which were found capable of reproducing the climatic spatial distribution and the longitudinal variability of the Siberian High from 1956 to 2005. The ensemble results show that the frequency of high SHPI winters and consequently more polluted conditions would increase by 29%, 61%, and 100% under RCP2.6, RCP4.5 and RCP8.5 until 2099. There are 11 out of the 25 GCMs examined here that project the possibility of high SHPI conditions to increase under RCP8.5. This indicates changes in the Siberian High position induced by increasing global greenhouse gas (GHG) emissions can lead to more winter pollution in North China in the future.
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