Single-atom nanozymes: classification, regulation strategy, and safety concerns.

Nanozymes, nanomaterials possessing enzymatic activity, have been studied extensively by researchers. However, their complex composition, low density of active sites, and inadequate substrate selectivity have hindered the maturation and widespread acceptance of nanozymes. Single-atom nanozymes (SAzymes) with atomically dispersed active sites are leading the field of catalysis due to their exceptional performance. The maximum utilization rate of atoms, low cost, well-defined coordination structure, and active sites are the most prominent advantages of SAzymes that researchers favor. This review systematically categorizes SAzymes based on their support type and describes their specific applications. Additionally, we discuss regulation strategies for SAzyme activity and provide a comprehensive summary of biosafety challenges associated with these enzymes.

[Distribution, Sources, and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Surface Waters of the Yinchuan Wetlands].

In order to explore the composition, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in water from Yinchuan wetlands, water samples were collected in the dry season and plentiful season from 15 wetlands. Sixteen species of PAHs were analyzed by gas-mass spectrometry, and source identification of PAHs was investigated by PCA and EPA positive matrix factorization 5.0. Ecological risk was assessed using the risk entropy method based on the neglected concentrations (NCs) and the maximum permissible concentrations (MPCs). The results showed that:① in the dry season, eight kinds of PAHs were detected, the concentrations of which ranged from 1455.38 ng·L-1to 2538.84 ng·L-1. In the plentiful season, 12 kinds of PAHs were detected, the concentrations of which ranged from 818.69 ng·L-1 to 1582.14 ng·L-1. The concentrations of PAHs in the dry season in Yinchuan were higher than that during the plentiful season. Compared with other domestic and overseas surface waters, PAH pollution was high; ② in the dry season, PAHs were mainly composed of 3-5 rings, and 2-3 and 4-6rings accounted for 35.6%-59.2% and 40.8%-59.7%, respectively. In the plentiful season, PAHs were mainly composed of 4-5 rings, and 2-3 and 4-6rings accounted for 10.2%-45.07% and 54.92%-89.76%, respectively; ③ the source analysis showed that in both the dry season and in the plentiful season, the main source were combustion and automobile emissions; ④ the ecological risk assessment indicated that the RQMPCs of BaA, BbF, InP, DBA, and BghiP during both the dry and plentiful seasons, and RQMPCs of Phe during the dry season, were higher than 1.0, indicating that attention needs to be paid to pollution levels. The RQNCs of Nap, Ace, Fla, Pyr, and BaP during the plentiful season and the RQNCs of Nap during the dry season were higher than 1.0, indicating the pollution risk was moderate and control and prevision of pollution from PAHs are required in the region.