1,679 research outputs found

    Phenolic compounds and its antioxidant activities in ethanolic extracts from seven cultivars of Chinese jujube

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    AbstractPhenolic compounds and its antioxidant activity of extracts from seven cultivars of Chinese jujubes were investigated by high performance liquid chromatography (HPLC) with standards and different antioxidant evaluation methods, such as phosphomolybdenum assay, superoxide radical scavenging activity (SRSA), hydroxyl radical scavenging activity (HRSA), antihemolytic activity and inhibition of lipid peroxidation in rat liver homogenate, respectively. The results showed the components of the extracts are comprised of total phenols and flavonoids, and its content ranges from 454.3 to 1298.9 (GAEmg/100g dry weight). Phlorizin, catechin, gallic acid, chlorogenic acid, caffeic acid were the predominant phenolic compounds. All the extracts had significant antioxidant activities either in vitro or in vivo. Correlation analysis indicated that the antioxidant capacities of Chinese jujube extracts demonstrated a good positive relationship with some phenolic acids, which was higher in Xiao and Goutou. The results indicated that Xiao and Goutou could be attributed to a potential source of natural antioxidants for food applications

    Bis[N′-(3-cyano­benzyl­idene)isonicotino­hydrazide-κN]silver(I) trifluoro­methane­sulfonate

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    In the title compound, [Ag(C14H10N4O)2]CF3SO3, two N atoms from two independent pyridyl rings of two N′-3-cyano­benzyl­ideneisonicotinohydrazide ligands coordinate to the unique AgI ion, forming a nearly linear coordination geometry. Adjacent silver complexes are primarily linked together by Ag⋯N inter­actions, with Ag⋯N separations of 2.877 (2) and 3.314 (2) Å. On the other hand, one CF3SO3 − anion inter­acts with hydrazone groups of two neighbouring ligands via N—H⋯O hydrogen bonds. These weak inter­molecular inter­actions contribute to the formation of supra­molecular chains. In addition, there are Ag⋯O inter­actions [2.787 (2) Å] between Ag and O atoms from adjacent chains

    Empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs and giants based on interferometric data

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    We present empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs of luminosity classes IV and V and for giants of luminosity classes II and III, based on a collection from the literature of about two hundred nearby stars with direct effective temperature measurements of better than 2.5 per cent. The calibrations are valid for an effective temperature range 3,100 - 10,000 K for dwarfs of spectral types M5 to A0 and 3,100 - 5,700 K for giants of spectral types K5 to G5. A total of twenty-one colours for dwarfs and eighteen colours for giants of bands of four photometric systems, i.e. the Johnson (UBVRJIJJHKUBVR_{\rm J}I_{\rm J}JHK), the Cousins (RCICR_{\rm C}I_{\rm C}), the Sloan Digital Sky Survey (SDSS, grgr) and the Two Micron All Sky Survey (2MASS, JHKsJHK_{\rm s}), have been calibrated. Restricted by the metallicity range of the current sample, the calibrations are mainly applicable for disk stars ([Fe/H]1.0\,\gtrsim\,-1.0). The normalized percentage residuals of the calibrations are typically 2.0 and 1.5 per cent for dwarfs and giants, respectively. Some systematic discrepancies at various levels are found between the current scales and those available in the literature (e.g. those based on the infrared flux method IRFM or spectroscopy). Based on the current calibrations, we have re-determined the colours of the Sun. We have also investigated the systematic errors in effective temperatures yielded by the current on-going large scale low- to intermediate-resolution stellar spectroscopic surveys. We show that the calibration of colour (gKsg-K_{\rm s}) presented in the current work provides an invaluable tool for the estimation of stellar effective temperature for those on-going or upcoming surveys.Comment: 28 pages, 19 figures, 8 tables, accepted for publication in MNRA
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