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In order to provide a theoretical basis for fertilizing and improving sandy fluvo-aquic soil quality, soil total nitrogen, content of different fractions of active organic nitrogen and soil δ15N values were determined after continuous application of nonhazardous composted sewage sludge (SW) in this study. Four-year field experiment was conducted in a wheat-maize rotation crop field during 2013-2016 in Henan province, China. Based on different fractions of soil active organic nitrogen and stable nitrogen isotope technology, and the response of soil physical and chemical properties, we studied the response of soil active organic nitrogen and soil δ15N values to composted sewage sludge. The results were that 1) Continuous application of SW significantly raised the content of soil carbon and nitrogen, with 265.83% and 284.31% increase, respectively, by the 45 t•hm-2 SW treatment in comparison with the control group (CK). The SW treatments significantly enhanced the active organic nitrogen component content and the particulate organic nitrogen (PON) by 104.57%-280.91%. The content of active nitrogen components in the treatment were presented as particulate organic nitrogen (PON)>light fraction organic matter nitrogen (LFON)>dissolved organic nitrogen (DON)>soil microbial biomass nitrogen (SMBN). The allocation of PON/TN and SMBN/TN increased, and the allocation of LFON/TN and DON/TN significantly decreased with the increasing application of SW, which resulted in decrease of the total distribution proportion of active nitrogen, indicating that the 45 t•hm-2 SW treatment contained enough stable organic nitrogen components for the accumulation of organic nitrogen. 2) Soil amended with SW significantly reduced soil δ15N values. The pathway analysis and the principal components analysis revealed that the rate of SW had a significantly effect on the soil δ15N values and soil nitrogen content, while correlation analysis showed that soil δ15N values had the strong relationship with the soil TN, PON and LFON contents, which indicated that the δ15N could reflected the effect of soil improvement with the SW. 3) Redundancy analysis further revealed that soil pH, soil moisture and soil fertility had significant effects on the content of soil active organic nitrogen fractions and their δ15N values. Soil pH and soil integrated fertility index (IFI) were the most significant factors influencing soil active organic nitrogen fractions and their δ15N values (P

Carbon monoxide (CO) gas therapy demonstrates great potential to induce cancer cell apoptosis and antitumor immune responses, which exhibits tremendous potential in cancer treatment. However, the therapeutic efficacy of CO therapy is inhibited by the immunosuppressive tumor microenvironment (TME). Herein, a facile strategy is proposed to construct hollow‐structured rough nanoplatforms to boost antitumor immunity and simultaneously reverse immunosuppression by exploring intrinsic immunomodulatory properties and morphological optimization of nanomaterials. The TME‐responsive delivery nanosystems (M‐RMH) are developed by encapsulating the CO prodrug within hollow rough MnO2 nanoparticles and the subsequent surface functionalization with hyaluronic acid (HA). Rough surfaces are designed to facilitate the intrinsic properties of HA‐functionalized MnO2 nanoparticles (RMH) to induce dendritic cell maturation and M1 macrophage polarization by STING pathway activation and hypoxia alleviation through enhanced cellular uptake. After TME‐responsive degradation of RMH, controlled release of CO is triggered at the tumor site for CO therapy to activate antitumor immunity. More importantly, RMH could modulate immunosuppressive TME by hypoxia alleviation. After the combination with aPD‐L1‐mediated checkpoint blockade therapy, robust antitumor immune responses are found to inhibit both primary and distant tumors. This work provides a facile strategy to construct superior delivery nanosystems for enhanced CO/immunotherapy through efficient activation of antitumor immune responses and reversal of immunosuppression. [ABSTRACT FROM AUTHOR]