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Flow duration curves (FDCs) that represent streamflow regime function through an empirical relationship between the FDC parameters and basin descriptors are widely adopted for hydrologic applications. However, the applications of this method are highly dependent on the availability of observation data. Hence, it is still of great significance to explore the process controls of underpinning regional patterns on streamflow regimes. In this study, we developed a new regionalization method of FDCs to solve the problem of runoff prediction for ungauged mountainous basins. Five empirical equations (power, exponential, logarithmic, quadratic, and cubic) were used to fit the observed FDCs in the 64 mountainous basins in eastern China, and the power model outperforms other models. Stepwise regression was used to explore the differentiated control of 23 basin descriptors on the 13 percentile flows of FDCs, and seven descriptors remained as independent variables for further developing the regional FDCs. Application results with different combinations of these selected descriptors showed that five indices, i.e., average annual rainfall (P), average elevation (H), average gradient (β), average topographic index (TI), and maximum 7d of annual rainfall (Max7d), were the main control factors of FDCs in these areas. Through the regional method, we found that 95.31% of all the basins have NSE values greater than 0.60 and ε (namely the relative mean square error) values less than 20%. In conclusion, our study can guide runoff predictions to help manage booming demands for water resources and hydropower developments in mountainous areas. [ABSTRACT FROM AUTHOR]

In mountainous basins with low anthropogenic influences, runoff generation varies geographically, and it is essential to investigate the hierarchical controls of geographical features on hydrological responses. In this study, a stepwise clustering scheme was proposed to classify 64 mountainous basins located in eastern China into 11 basin groups and 3 hierarchies according to the geographical features of rainfall, topography and geomorphology, and soil and geology. Then, the leave-one cross validation assessing the transferability of hydrological model parameters was used to measure the hydrological similarity among basins and within each group, and to examine the quality of classification. The results showed that 92% of all basins had other basins with high similarity. The overall similarity of the hydrological responses in the 11 basin groups was quite different. The basin groups driven by heavy rainfall events tended to form highly similar runoff processes. Basins in the groups with steeper terrain, more convergent slopes, rounder shapes, and better vegetation cover also exhibited a higher overall hydrological similarity. Then, according to the discharge characteristics, the controlling role and intensity of different hierarchical geographical features on hydrological responses were quantitatively represented. In 6 of the 11 basin groups, rainfall features (e.g. average monthly rainfall and rainstorm characteristics) were collectively the primary controlling factor of runoff, while topographic and geomorphic features were the second most important factor. Rainfall features were the second most important controlling factor in the other four basin groups. However, the controlling role of soil and geological features on hydrological responses appeared to be unstable. In summary, these findings could provide guidance for hydrological predictions in ungauged basins in diverse geographical environments. [ABSTRACT FROM AUTHOR]

Background : Sonodynamic therapy (SDT) is a promising strategy to inhibit tumor growth and activate antitumor immune responses for immunotherapy. However, the hypoxic and immunosuppressive tumor microenvironment limits its therapeutic efficacy and suppresses immune response. Methods: In this study, mitochondria-targeted and ultrasound-responsive nanoparticles were developed to co-deliver oxygen (O 2 ) and nitric oxide (NO) to enhance SDT and immune response. This system (PIH-NO) was constructed with a human serum albumin-based NO donor (HSA-NO) to encapsulate perfluorodecalin (FDC) and the sonosensitizer (IR780). In vitro , the burst release of O 2 and NO with US treatment to generate reactive oxygen species (ROS), the mitochondria targeting properties and mitochondrial dysfunction were evaluated in tumor cells. Moreover, in vivo , tumor accumulation, therapeutic efficacy, the immunosuppressive tumor microenvironment, immunogenic cell death, and immune activation after PIH-NO treatment were also studied in 4T1 tumor bearing mice. Results: PIH-NO could accumulate in the mitochondria and relive hypoxia. After US irradiation, O 2 and NO displayed burst release to enhance SDT, generated strongly oxidizing peroxynitrite anions, and led to mitochondrial dysfunction. The release of NO increased blood perfusion and enhanced the accumulation of the formed nanoparticles. Owing to O 2 and NO release with US, PIH-NO enhanced SDT to inhibit tumor growth and amplify immunogenic cell death in vitro and in vivo . Additionally, PIH-NO promoted the maturation of dendritic cells and increased the number of infiltrating immune cells. More importantly, PIH-NO polarized M2 macrophages into M1 phenotype and depleted myeloid-derived suppressor cells to reverse immunosuppression and enhance immune response. Conclusion: Our findings provide a simple strategy to co-deliver O 2 and NO to enhance SDT and reverse immunosuppression, leading to an increase in the immune response for cancer immunotherapy., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)