Direct and indirect monitoring methods for nitrous oxide emissions in full-scale wastewater treatment plants: A critical review.

Mitigation of nitrous oxide (N2O) emissions in full-scale wastewater treatment plant (WWTP) has become an irreversible trend to adapt the climate change. Monitoring of N2O emissions plays a fundamental role in understanding and mitigating N2O emissions. This paper provides a comprehensive review of direct and indirect N2O monitoring methods. The techniques, strengths, limitations, and applicable scenarios of various methods are discussed. We conclude that the floating chamber technique is suitable for capturing and interpreting the spatiotemporal variability of real-time N2O emissions, due to its long-term in-situ monitoring capability and high data acquisition frequency. The monitoring duration, location, and frequency should be emphasized to guarantee the accuracy and comparability of acquired data. Calculation by default emission factors (EFs) is efficient when there is a need for ambiguous historical N2O emission accounts of national-scale or regional-scale WWTPs. Using process-specific EFs is beneficial in promoting mitigation pathways that are primarily focused on low-emission process upgrades. Machine learning models exhibit exemplary performance in the prediction of N2O emissions. Integrating mechanistic models with machine learning models can improve their explanatory power and sharpen their predictive precision. The implementation of the synergy of nutrient removal and N2O mitigation strategies necessitates the calibration and validation of multi-path mechanistic models, supported by long-term continuous direct monitoring campaigns.

Baicalein mediates inhibition of migration and invasiveness of skin carcinoma through Ezrin in A431 cells.

BACKGROUND: Ezrin is highly expressed in skin cancer and promotes tumor metastasis. Ezrin serves as a promising target for anti-metastasis therapy. The aim of this study is to determine if the flavonoid bacailein inhibits the metastasis of skin cancer cells through Ezrin. METHODS: Cells from a cutaneous squamous carcinoma cell line, A431, were treated with baicalein at 0-60 µM to establish the non-cytotoxic concentration (NCC) range for baicalein. Following treatment with baicalein within this range, total Ezrin protein (both phosphorylated and unphosphorylated forms) and phosphorylated-Ezrin (phos-Ezrin) were detected by western blotting, and Ezrin RNA was detected in A431 cells using reverse transcription-polymerase chain reaction (RT-PCR). Thereafter, the motility and invasiveness of A431 cells following baicalein treatment were determined using wound-healing and Boyden chamber invasion assays. Short-interfering RNA (si-RNA) specifically targeting Ezrin was transfected into A431 cells, and a si-RNA Ezrin-A431 cell line was established by G418 selection. This stable cell line was transiently transfected with Ezrin and mutant Ezrin plasmids, and its motility and invasiveness was subsequently determined to clarify whether bacailein inhibits these processes through Ezrin. RESULTS: We determined the range of NCCs for baicalein to be 2.5-40 µM in A431 cells. Baicalein displayed a dose- and time-dependent inhibition of expressions of total Ezrin and phos-Ezrin within this range NCCs. In addition, it exerted this inhibitory effect through the reduction of Ezrin RNA transcript. Baicalein also inhibited the motility and invasiveness of A431 skin carcinoma cells within the range of NCCs, in a dose- and time-dependent manner. A431 cell motility and invasiveness were inhibited by 73% and 80% respectively when cells were treated with 20 µM baicalein. However, the motility and invasiveness of A431 cells containing the Ezrin mutant were not effectively inhibited by baicalein. CONCLUSIONS: Baicalein reduces the migration and invasiveness of A431 cells through the inhibition of Ezrin expression, which leads to the suppression of tumor metastasis.