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  • Author or Editor: Y. Xu-Wu x
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Abstract  

The combustion energy of thioproline was determined by the precision rotating-bomb calorimeter at 298.15 K to be Δc U= –2469.301.44 kJ mol–1. From the results and other auxiliary quantities, the standard molar enthalpy of combustion and the standard molar enthalpy of formation of thioproline were calculated to be Δc H m θC4H7NO2S, (s), 298.15 K= –2469.921.44 kJ mol–1 and Δf H m θC4H7NO2S, (s), 298.15K= –401.331.54 kJ mol–1.

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Garlic is widely used as food flavouring, and China is the world's largest garlic producer and exporter. To develop a convenient technique for evaluation of garlic cultivars would be worthwhile, and it would have wide application in such a huge market. In this research, 3D front-face fluorescence data of 8 garlic cultivars were recorded, and independent component analysis was used to decompose the overall fluorescence spectra into six independent components. The first, second, and fourth independent components showed a big difference among the cultivars, and the chemical fluorophores behind these three components were specified as protein, vitamin B6, and ATP, respectively, as fluorescent markers for evaluation. The result showed that all 8 cultivars cluster separately. The cultivar “YNQJ” have the highest quality in terms of protein and vitamin B6, “NXYC” and “SDHB” have the highest content of ATP, while “SXXA” is the poorest in terms of protein and ATP, and “HNJZ” has the lowest content of vitamin B6. Therefore, rapid evaluation of garlic cultivars can be accomplished successfully by using only the proportion values of three properly selected fluorescent markers.

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Changes in microbial population, pH, sugar, organic acid, anthocyanins, total soluble phenolics, and anti-glucosidase contents were measured during fermentation of mulberry juice at 30 °C by probiotic Leuconostoc mesenteroides showing rapid growth after an approximately 1-day lag phase and reaching a maximum of 8.6 log CFU ml−1 after 4 d. During the rapid growth phase, the main mulberry juice sugars, glucose and fructose, were largely consumed, and the acidic metabolites, lactic acid and acetic acid, were produced accordingly. A slow decrease in the concentration of the main organic acid, citric acid, was also observed during fermentation. After 4 d fermentation, anthocyanin content showed a 44.4% reduction, but the total amount of soluble phenolics and α-glucosidase inhibitory activity showed no significant changes (P>0.05). This suggests that L. mesenteroides fermentation of mulberry juice is a good strategy to enhance its probiotic value and to decrease the sugar content without changing the anti-glucosidase activity, which is required to reduce postprandial rise in blood glucose.

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Abstract  

The copper(II) complex of 6-benzylaminopurine (6-BAP) has been prepared with dihydrated cupric chloride and 6-benzylaminopurine. Infrared spectrum and thermal stabilities of the solid complex have been discussed. The constant-volume combustion energy, Δc U, has been determined as −12566.92±6.44 kJ mol−1 by a precise rotating-bomb calorimeter at 298.15 K. From the results and other auxiliary quantities, the standard molar enthalpy of combustion, Δc H m θ, and the standard molar of formation of the complex, Δf H m θ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol−1, respectively.

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Abstract  

The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III) uptake on soil, however at low pH values, the influence of anions was following the order: Cl ≈ NO3  > ClO4 . In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7, the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8.

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Summary

Oroxylin A (5,7-dihydroxy-6-methoxyflavone), which has showed multiple pharmacological effects, was semi-synthesized chemically as a pharmaceutical agent. Its impurities, degradation products and their formation pathways remain unknown. In the present study, two impurities (5,6,7-trihydroxyflavone, 5-hydroxy-6,7-dimethoxytlavone) and a degradation product (5,7-dihydroxy-8-methoxyflavone) in Oroxylin A bulk drug substance were identified, and their formation pathways were proposed. A reversed phase liquid chromatographic method for the simultaneous determination of Oroxylin A and the three compounds was developed on a C18 column using methanol-acetonitrile-0.1% acetic acid (54:23:23, v/v/v) as the mobile phase. The detection was performed at 271 nm. The method was validated to be robust, precise, specific and linear between 4 and 40 μg mL−1; the limits of detection and quantification of Oroxylin A were 0.01 and 0.04 μg mL−1, respectively. The developed method was found to be suitable to check the quality of bulk samples of Oroxylin A at the time of batch release and also during its stability studies (long term and accelerated stability).

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Abstract  

Solvent extraction of protactinium with tri-iso-octyl-amine (TIOA) in xylene, benzene, carbon tetrachloride and chloroform from HCl, HF, HNO3, HClO4 and H2SO4 media was studied using 233Pa as a radiotracer. The extraction efficiencies of protactinium were determined as a function of shaking time, concentrations of mineral acids in aqueous phase, extractant concentrations and diluents in organic phase. The extraction mechanism was discussed. The results show that the extracted species in the organic phase is [(R3NH)nPa(OH)xCl y 5−xy ].

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Abstract  

The constant-volume combustion energies of the lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine (4HDNPPb), ΔUc (2HDNPPb(s) and 4HDNPP(s)), were determined as –4441.922.43 and –4515.741.92 kJ mol–1 , respectively, at 298.15 K. Their standard enthalpies of combustion, Δcm H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K), and standard enthalpies of formation, Δrm H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K) were as –4425.812.43, –4499.631.92 kJ mol–1 and –870.432.76, –796.652.32 kJ mol–1 , respectively. As two combustion catalysts, 2HDNPPb and 4HDNPPb can enhance the burning rate and reduce the pressure exponent of RDX–CMDB propellant.

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