No abstract

Soil microbes greatly contribute to the regulating of phosphorus (P) cycling, which plays a significant role in maintaining wetland ecosystem processes and function. The microbial functional diversity of soil P cycling in response to wetland degradation, however, remains largely unknown. We used metagenomic sequencing to investigate the microbial community and genes related to soil P cycling in un-degraded marshes and meadows derived from long-term marsh degradation in the Lalu alpine wetland of the Tibetan Plateau. When the marsh degraded into meadow, organic P (OP) mineralization genes increased while genes related to P-starvation response regulation decreased. Proteobacteria (20.5-74.3%) and Actinobacteria (5.6-59.7%) were the dominant phyla in soils and were also the main contributors (39.7-84.1% in total) to soil P-cycling genes. Soil pH was the primary factor influencing the P-cycling functional genes. Soil pH negatively affected the genes related to the P-uptake and transport system and had negative effects on the genes related to P-starvation response regulation, OP mineralization, and inorganic P solubilization. These findings may deepen our understanding of the biogeochemical process of soil OP and may be beneficial for wetland management.

Metal halide perovskites show considerable optical nonlinearity and could be used for cost-effective nonlinear optical devices if their nonlinear susceptibilities can be improved. Here, we report large optical nonlinearity, including third-order nonlinear absorption, refraction, and two-photon absorption excited luminescence, of CsPbBr3 nanoplatelets with a thickness of two or three atomic layers and a plane size of about 60 nm. Specifically, the nonlinear absorption was mainly induced by two-photon absorption at low incident powers, and the nonlinear absorption cross section reached 2.15 × 107 GM. It is two orders of magnitude larger than that of CsPbBr3 nanocrystals, which makes them an ideal optical limiting material. Furthermore, the nanoplatelets exhibited large self-phase modulation-induced nonlinear refraction, and the figures of merit W and T satisfied W >1 and T <1, which allow for optical switching. The large optical nonlinearity of CsPbBr3 nanoplatelets provides a basis for multifunctional applications in nonlinear optical devices.