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Mounting evidence shows that tumor hypoxia stress promotes tumor invasion and metastasis and induces therapeutic resistance. Oxygen-independent Fenton reaction, which refers to the iron-catalyzed conversion of endogenous hydrogen peroxide (H 2 O 2) to hydroxyl radical (·OH), has been designed for ferroptosis therapy. Nevertheless, the treatment efficiency is compromised by limited H 2 O 2 content and limited tumor retention and penetration of nanoparticles. Herein, we designed a tumor-acidity and bioorthogonal chemistry mediated construction and deconstruction of drug depots for tumor ferroptosis under normoxia and hypoxia. Briefly, the dendritic poly(amidoamine) (PAMAM, G4) was modified using cinnamaldehyde (CA) to deplete GSH and increase H 2 O 2 levels, and ferrocene (Ferr) served as Fenton reaction catalyst to generate PFC. Subsequently, PFC was modified with maleic acid amide with slow pH-response rate and poly(2-azepane ethyl methacrylate) (PAEMA) with rapid pH-response rate, accompanied with highly efficient bioorthogonal chemistry to construct and deconstruct drug depots for enhanced tumor retention and penetration. The small-sized PFC potentially induced H 2 O 2 self-supplied ferroptosis under normoxia and hypoxia. In sum, this work utilizes two tumoral acidity-responsive groups with different response rates and highly efficient bioorthogonal click chemistry, which paves a way for ferroptosis and provides a general drug delivery strategy with enhanced tumor retention and penetration. Oxygen independent Fenton reaction refers to the conversion of endogenous H 2 O 2 to ·OH which has been designed for ferroptosis therapy. Nevertheless, limited H 2 O 2 level and abundant GSH in tumor cells could both compromise the treatment efficiency. Herein, we developed a tumor-acidity and bioorthogonal chemistry mediated construction and deconstruction of drug depots, which elevate the intracellular H 2 O 2 level and deplete GSH for tumor ferroptosis under normoxia and hypoxia microenvironment. This work utilizes two tumoral acidity response groups with different response rates and highly efficient bioorthogonal click reactions, which paves a way for tumor cell ferroptosis and provides a general drug delivery strategy for enhanced tumor accumulation and penetration. [Display omitted] [ABSTRACT FROM AUTHOR]

For the accurate calculation of CO 2 emission in utility boilers, the calculation model of CO 2 emission suitable for most coal-fired boilers is built. In this model, BP neural networks were adopted to predict the carbon content of burning coal. This model took the proximate analysis data and fuel consumption flow / coal consumption as inputs, and output the CO 2 emission. Under the BP network prediction model, the average difference of carbon content of burning coal was about 1.80%, while that of CO 2 emission were 3.92% and 0.96%. Compared with emission factor method and capacity standard method, the method in this paper is more suitable to count the CO 2 emission of utility boilers. [ABSTRACT FROM AUTHOR]