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The study was carried out to evaluate the pharmacokinetic disposition of enrofloxacin (ENF) with a single dose of 20 mg/kg after oral administration in largemouth bass (Micropterus salmoides) at 28°C. The concentrations of ENF and of its metabolite ciprofloxacin (CIP) in plasma, liver, and muscle plus skin in natural proportions were determined using HPLC. The concentration-time data for ENF in plasma were best described by a two-compartment open model. After oral administration, the maximum ENF concentration (Cmax ) of 10.99 μg/ml was obtained at 0.60 hr. The absorption half-life (T1/2Ka ) of ENF was calculated to be 0.07 hr whereas the elimination half-life (T1/2β ) of the drug was 90.79 hr. The estimates of area under the plasma concentration-time curve (AUC) and apparent volume of distribution (Vd/F) were 1,185.73 μg hr/ml and 2.21 L/kg, respectively. ENF residues were slowly depleted from the liver and muscle plus skin of largemouth bass with the T1/2β of 124.73 and 115.14 hr, respectively. Very low levels of ciprofloxacin were detected in the plasma and tissues. A withdrawal time of 24 days was necessary to ensure that the residues of ENF + CIP in muscle plus skin were less than the maximal residue limit (MRL) of 100 μg/kg established by the European Union.

The hotspot recognition algorithm is proposed based on a potential collision in order to study the aircraft taxi conflicts in large airports. The spatial and temporal distribution characteristics of hotspots are analyzed based on the risk assessment model of hotspot constructed in this paper. Firstly, approaches for monitoring of the aerodrome movement were compared. The hotspot recognition algorithm taken into account of whether aircrafts’ taxi track has spatial and temporal overlap based on the aerodrome surveillance radar (ASR) data was presented, by identifying the hotspots through analyzing whether the aircrafts’ time of entering and exiting the same taxiway is overlap or not, and the heading difference and distance of the two aircrafts satisfy the specified threshold constraint condition. Then, the ASR data were divided into several parts, and then airport hotspots were recognized and the spatial and temporal distribution characteristics were analyzed. The risk assessment model of airport safety hotspots was constructed which is taken into account of the conflict probability and its severity consequence. Finally, based on the risk grade assessment criteria and hotspots’ risk value, the risk grade ranking of hotspot in one airport of China was evaluated and designated. According to the result, the spatial and temporal distribution characteristics of airport hotspots were varied with the variation of airport traffic flow and operational mode of runway, which shows that the hotspots have the characteristics of dynamic periodicity and diurnal variation. And the risk assessment results were consistent with experts’ opinions and actual operation condition, which verified the rationality of the hotspot recognition algorithm, risk assessment model as well as the risk grade ranking criteria.

By embedding a fibre Bragg grating (FBG) sensor which had been recalibrated at cryogenic temperatures in the cement-based materials to be tested, the thermal strain of cement-based materials and the factors affecting it could be effectively measured under cryogenic temperatures for its freeze-thaw cycles. The freezing process of pore water was characterized by a differential scanning calorimeter (DSC), and the ice content was calculated by thermoporometry (TPM). The relationship between the freezing process of pore water and the thermal strain was discussed. The results confirmed that FBG sensors could characterize the on-time thermal strain of cement-based materials under cryogenic temperatures. The moisture content and fine aggregate had a great influence on the thermal strain under cryogenic temperatures and its freeze-thaw cycles. Cement paste expanded from −25 °C to −50 °C in the cooling period and contracted from −50 °C to −5°C in the heating period. The residual strain remained in the matrix generated by water freezing between 0℃ and −50℃ after six cryogenic freeze-thaw cycles. Greater thermal strain was generated in the cement paste with a higher moisture content, and fine aggregate obviously increased the thermal strain of cement-based materials. The migration and freezing of pore water are the main reasons for the thermal strain of cement-based materials at cryogenic temperatures.

In this work, a reliable and affordable QuEChERS sampling method is developed for simultaneous detection and quantification of 13 perfluorinated compounds (PFCs) in aquatic products. Liquid chromatography/tandem mass spectrometry (LC-MS/MS) was used for rapid analysis and the analytes were extracted using styrene-divinylbenzene copolymer (PS-DVB). The performances of the sorbents were evaluated based upon parameters, such as recovery and matrix effect. Under optimized conditions, the limits of detection of 13 PFCs were found to be lying within the range of 0.001–0.070 μg kg−1. The application of aquatic sampling demonstrated that ultra-trace levels of PFCs were successfully detected and quantified within the range of 0.028–31.0 μg kg−1 in tilapia (Oreochromis niloticus), salmon (Oncorhynchus mykiss), mussels (Perna viridis) and clam (Ruditapes philippinarum). Compared with the solid phase extraction method, the application of PS-DVB beads as an adsorbent proved to be quicker and successful in the determination of PFCs in aquatic samples.