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Objective: This study aimed to improve the safety supervision of cadmium in milk samples. Methods: A liquid-liquid microextraction method based on hydrophobic deep eutectic solvent （DES） was developed for the determination of cadmium in milk samples by graphite furnace atomic absorption spectrometry. The types of deep eutectic solvents were selected for high extraction efficiencies and it was found that DES composed of thymol and lactic acid at the molar ratio of 1∶1 provided higher extraction efficiency. In addition, several important experimental conditions including the volume of DES, sample pH value, the pretreatment methods of samples were optimized. Results: Under the optimized conditions, Cd had good linearity in the range of 0~3.0 ng/mL, and the correlation coefficient was 0.998. The detection limit was 0.02 μg/kg. The recoveries ranged from 94.7% to 113.0% with relative standard deviations （RSD） of 0.38%~7.00%. Conclusion: With the advantages of simplicity, rapidness, exactness and low detection limit, this method could be used for the detection of cadmium in milk samples.

In the heterostructure composed of metal and one-dimensional photonic crystal (1DPC), the optical Tamm state (OTS) can be excited directly without the coupling of prism or grating, but it is strongly dependent on the photonic band gap (PBG) of the 1DPC. In particular, the PBG of the all-dielectric 1DPC as well as the corresponding OTSs shift toward shorter wavelengths for both transverse magnetic (TM) and transverse electric (TE) polarizations as the angle of incidence increases, making it impossible to achieve a high-performance polarization selection. In a heterostructure consisting of a silver layer and an ITO-based one-dimensional photonic hypercrystal (1DPHC), we experimentally observe for the first time that the OTSs are red-shifted for TM polarization and blue-shifted for TE polarization with increasing incident angle. The ITO-based 1DPHC possesses a large red-shifted PBG in the near-infrared region, which guarantees the full excitation of the OTSs at different angles. Our work provides a potential direction for improving the sensitivity, polarization selection and operating angle range of the Tamm sensor.

The paper reviews the mechanism and research progress of activation of persulfate by applying Fe, n-ZVI, heat and alkali, analyses the effects of persulfate on soil physicochemical properties and micro-organisms, describes the combined application with surfactant drenching and bioremediation, and points out some research hotspots for the remediation of contaminated soils by persulfate oxidation technology. [ABSTRACT FROM AUTHOR]

Understanding vegetation water utilization can provide scientific basis for vegetation protection and rational distribution of water resources in arid desert oasis area. In this study, sapling (DBH≤10 cm), mature (10 cm40 cm) Populus euphratica were chosen as sample trees in natural oasis of Dariaboui. We measured oxygen isotopes of xylem water and potential water sources (surface water, soil water in 0-3 m soil layer and groundwater) of P. euphratica with different tree ages. The IsoSource model was used to study water sources of P. euphratica . The results showed that soil water content increased with increasing soil depth, while the δ 18 O value of soil water decreased firstly and then stabilized. When groundwater depth was 2 m, the δ 18 O value of xylem water increased with increasing tree ages. When the depths of groundwater were 4.2 and 8 m, the δ 18 O values of xylem water decreased with increasing tree ages. Water sources of P. euphratica varied across tree age. When the depth of underground water was 2 m, the main water source for young trees was surface water, and the contribution proportion was 64.7%. For mature and overmature trees, it was deep soil water and ground-water, with a contribution of about 30%. When the depth of groundwater was 4.2 m, the main water sources of P. euphratica of different tree ages were deep soil water and groundwater, and the contribution proportion was about 30%. The lowest contribution of P. euphratica of different tree ages was shallow soil water, accounting for about 10%.