531 research outputs found

    Identification of urinary and feces metabolites of Rhizoma Paridis saponins in rats based on ultra high performance liquid chromatography/time-of-flight mass spectrometry (UPLC/Q-TOF/MS)

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    An ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/QTOF/MS) method was established to analyze the saponins in Rhizoma Paridis saponins (RPS) and the constituents in urinary and feces samples. As we know, the constituents of traditional Chinese medicines are very complex and pre-clinical research including metabolism, excretion and pharmacokinetics of herbal medicine components are of great importance in understanding their biological effects and safety. Therefore, deduction of the metabolic and excretive processes of RPS are necessary. As a result, twenty-two original saponins were detected in RPS-treated urinary and feces. Four excreta were observed in rat feces. Therefore, most original saponins and little deglycosylated saponins have been excreted in the rat urine and feces.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Preparation of N-, O-, and S-tri-doped biochar through one-pot pyrolysis of poplar and urea formaldehyde and its enhanced removal of tetracycline from wastewater

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    In this study, biochar was prepared via hybrid doping of N, O, and S by applying one-pot pyrolysis of poplar wood and S-containing urea formaldehyde at 900 °C. Different doping ratios were adopted, and the contents of O, N, and S were in the ranges of 2.78 – 5.56 %, 2.16 – 4.92 %, and 1.42 – 4.98 %, respectively. This hybrid doping significantly enhanced the efficiency of the removal of tetracycline (40 mg/L) from wastewater to 71.84 % in comparison with that attained by using normal poplar biochar (29.45 %). The adsorption kinetics and isotherms indicated that the adsorption process was favorable and was dominated by chemisorption instead of physisorption; the dominant adsorption process may be justified by the existence of abundant functional groups. The adsorption capacity was barely related to the surface area (R2 = 0.478), while it was closely related to the concentration of graphitic N (R2 = 0.985) because graphitic N enhanced the π–π interactions. The adsorption capacity was also highly related to the proportion of oxidized N and oxidized S owing to hydrogen bonding, which may have overlapped with the contribution of O-containing functional groups. This study presents a simple hybrid doping method for biochar modification and provides fundamental insights into the specific effects of O-, N- and S-containing functional groups on the performance of biochar for tetracycline removal

    Influence Maximization with Novelty Decay in Social Networks

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    Influence maximization problem is to find a set of seed nodes in a social network such that their influence spread is maximized under certain propagation models. A few algorithms have been proposed for solving this problem. However, they have not considered the impact of novelty decay on influence propagation, i.e., repeated exposures will have diminishing influence on users. In this paper, we consider the problem of influence maximization with novelty decay (IMND). We investigate the effect of novelty decay on influence propagation on real-life datasets and formulate the IMND problem. We further analyze the problem properties and propose an influence estimation technique. We demonstrate the performance of our algorithms on four social networks
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