AbstractCiprofloxacin (CPFX) and enrofloxacin (ENFX), two of the most widely used fluoroquinolones (FQs), pose a great threat to humans and the ecosystem. In this study, the toxic mechanisms between the two FQs and trypsin were evaluated by means of multiple spectroscopic methods, as well as molecular docking. During the fluorescence investigations, both FQs quenched the intrinsic fluorescence of trypsin effectively, which was due to the formation of moderately strong complexes (mainly through van der Waals forces and hydrogen bonds). The binding of two FQs not only caused the conformational and micro-environmental changes of trypsin, but also changed its molecular activity; shown by the UV–Visible absorption spectroscopy, synchronous fluorescence spectroscopy, and functional tests. The established methods in this work can help to comprehensively understand the transport of FQs in the human body. 相似文献
Heavy metal(loid) extraction from soils in overlapped areas of farmland and coal resources (OAFCR) is crucial in understanding heavy metal bioavailability in soil and the subsequent risks to crops and consumers. However, limited attention has been paid to the extraction procedure of heavy metal(loid)s in OAFCR soils in the research. This study therefore explored different single and mixed extraction procedures, such as acetic acid (HOAc), citric acid, ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA), ethylene diamine tetraacetic acid + ammonium acetate (EDTA+NH4OAc), and total digestion (HNO3-HClO4-HF) to determine the bioavailability of As, Cd, Cr, Cu, Pb, and Zn in OAFCR soil in Xuzhou, China. The results showed the metal(loid) extraction capacity from soil of the different procedures could be ranked as AB-DTPA > EDTA+NH4OAc > HOAC > citric acid. The transfer ability of heavy metal(loid)s from soil to wheat tissues and from wheat roots to aerial parts was analyzed by calculating the bioconcentration factor and transfer factor, respectively. Transfer factors of all metal(loid)s were < 1 except Cr whose transfer factor from root to shell and straw were > 1. It is suspected that foliar uptake plays a dominant role in Cr uptake. Correlation analysis between the bioavailability of heavy metal(loid)s in soil and uptake in respective wheat tissues was performed to recommend the best extraction procedures for different studies. The results show that AB-DTPA extraction is recommended for Cu uptake to wheat roots, straws, shells and grains, Zn uptake to roots, and Cd uptake to roots and straws.
Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau, further affecting the water resource supply. However, the related studies on carbonaceous matter are still scarce in Geladaindong (GLDD) region, the source of the Yangtze River. Therefore, the concentration, source and variations of carbonaceous matter at Ganglongjiama (GLJM) glacier in GLDD region were investigated during the melting period in 2017, which could deepen our understanding on carbonaceous matter contribution to glacier melting. The results showed that dissolved organic carbon (DOC) concentration of snowpit samples (283?±?200?μg/L) was much lower than that of precipitation samples (624?±?361?μg/L), indicating that large parts of DOC could be rapidly leached from the snowpit during the melting process. In contrast, refractory black carbon (rBC) concentration measured by Single Particle Soot Photometer of snowpit samples (4.27?±?3.15?μg/L) was much higher than that of precipitation samples (0.97?±?0.49?μg/L). Similarly, DOC with high mass absorption cross-section measured at 365?nm value was also likely to enrich in snowpit during the melting process. In addition, it was found that both rBC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became stronger. Therefore, rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting process. Based on relationship among DOC, rBC and K+ in precipitation, the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period. 相似文献