Spatial effects and impact factors of food nitrogen footprint in China based on spatial durbin panel model.

Reactive nitrogen (Nr) has far-reaching advantages and disadvantages on human beings. Nitrogen footprint (NF) is a tool to quantify the use of Nr in the environment. Food nitrogen footprint (FNF) accounts for the largest proportion of the total NF, and the differences between provinces in China exist objectively. In order to explore the spatial correlation and socio-economic driving factors of China's FNF, this paper uses N-calculator tool to calculate the FNF of 30 provinces in China from 2000 to 2018, and uses exploratory spatial data to analyze the spatial correlation and changes of provincial FNF, The driving factors and spatial effects of FNF change in the province were analyzed by using spatial Durbin panel model and spatial regression partial differential method. The results showed that: (1) There is a significant and stable positive spatial dependence and heterogeneity in the FNF among provinces; (2) The direct effect factors of promoting the growth of FNF in the province are urban household Engel coefficient, per capita disposable income of rural residents and rural household Engel coefficient. The main factors of restraining the growth of FNF in the province are wastewater discharge per unit GDP and per capita GDP; (3) the spillover effect is mainly manifested as the negative effect of the increase of urban household Engel coefficient on neighboring provinces, and the spillover effect of per capita disposable income of urban residents and nitrogen fertilizer application rate per unit grain yield on the growth of FNF of neighboring provinces is significant. From the policy level, it is necessary to guide healthy and scientific eating habits, reduce the proportion of meat and fish in the diet structure, reduce the nitrogen fertilizer application per unit grain yield, and improve the efficiency of chemical fertilizer utilization. When formulating relevant policies, government departments should give consideration to the cooperation between provincial and regional governments.

Enantioselective Synthesis of Pyrazolo[3,4-b]pyridone Derivatives with Antifungal Activities against Phytophthora capsici and Colletotrichum fructicola.

A chiral NHC-catalyzed [3 + 3] cycloaddition reaction is developed for the efficient synthesis of pyrazolo[3,4-b]pyridones in generally excellent yields and optical purities. The R, S, and racemic forms of these molecules are systematically studied via in vitro tests that detect antifungal activity against Phytophthora capsici and Colletotrichum fructicola. Chiral compounds (R)-3i, (R)-3j, and (R)-3p are identified to have excellent inhibitory effects against P. capsici and C. fructicola.

NHC-Catalyzed Cascade Reaction between ß-Methyl Enals and Dienones for Quick Construction of Complex Multicyclic Lactones.

A NHC-promoted cascade reaction between ß-methyl enal and dienone is developed for quick access to multicyclic lactone molecules bearing quaternary chiral carbon centers. Our study constitutes the first 1,6-addition of the acylazolium vinyl enolate γ-carbon via NHC catalysis and provides rapid access to complex lactone molecules that are otherwise difficult to prepare. The structurally sophisticated lactone products bearing up to four fused ring structures are afforded in up to quantitative yields with good to excellent enantioselectivities.

Purification and rapid dissolution of potassium sulfate in aqueous solutions.

Water soluble potassium sulfate dissolves rapidly and completely in water. Its main characteristics are purity and dissolution rate. In this study, the purification and rapid dissolution of potassium salt (K2SO4) separated from potassium brine deposits collected from Lop Nur basin of China (referred to as LN K2SO4) were studied for utilization in agricultural farming as a potash fertilizer. First, the dissolving-crystallizing process was conducted to remove the insoluble content and improve the purity of K2SO4. Second, physical modification of K2SO4 surfaces was accomplished based on the Noyes-Whitney equation. The results showed that the water insoluble content could be completely removed and the purity of K2SO4 reached 100% in the purification process. The dissolution rate was significantly improved with the help of environmentally-friendly additives such as sodium tripolyphosphate (STPP)/urea phosphate (UP). These additives ameliorated the diffusion coefficient (D) and the diffusion layer thickness (h) for K2SO4. Results also demonstrated that a larger K2SO4 surface area (S) induced a higher dissolution rate.

Improvement of sylvite flotation from halite by starvation feeding the collector octadecylamine.

In order to improve the separation of sylvite and halite in SDIC Xinjiang Lop Nur potash Co. Ltd. (SLNP), in this work, the flotation kinetics of sylvite and halite under different collector dosages were investigated. It was observed that the increased speed of halite was much faster than sylvite in terms of flotation rate with an increase in octadecylamine hydrochloride (ODA) dosage. The reason for the upward floating of halite explored by SEM-EDS was that sylvite was locked with halite, thus it can float up along with sylvite. According to the analysis results, a strategy of starvation feeding the collector was employed to increase the flotation rate difference between sylvite and halite, and consequently improve the separation of sylvite and halite. It has been demonstrated that starvation feeding the collector is an efficient method for obtaining high grade sylvite, because it can not only improve the separation of sylvite and halite but also decrease the consumption of ODA in the flotation process.

Creation of Hollow Calcite Single Crystals with CQDs: Synthesis, Characterization, and Fast and Efficient Decontamination of Cd(II).

In this work, carbon quantum dots were first prepared through one-pot hydrothermal route of the propyl aldehyde and sodium hydroxide via an aldol condensation reaction, and a novel solid-phase extraction adsorbent of hollow calcite single crystals was prepared via the precipitation of metal nitrates by the CO2 diffusion method in the presence of CQDs and further applied for excessive Cd(II) ions removal from water. The spectra and morphologies of the etched calcite were investigated by X-ray diffraction, Fourier transform infrared spectrometry, Scanning electron microscope, and Transmission electron microscopy. The results show that the CQDs etching technique successfully furnish a strategy for manufacturing interface defects onto the calcite crystal. Bath studies were done to evaluate the effects of the major parameters onto Cd(II) adsorption by the etched calcite, such as pH, contact time, and initial Cd(II) concentration. The Cd(II) adsorption onto the new adsorbent could reach a maximum adsorption amount of 66.68 mg/g at 120 min due to the abundant exterior adsorption sites on the adsorbent. The adsorption kinetics and adsorption isotherms of Cd(II) on the etched calcite were also investigated. The experimental datum showed that the adsorption kinetics and isotherms of Cd(II) on the etched calcite were well-fitted by the pseudo-second-order kinetic model and the Freundlich isotherm model respectively. The adsorption mechanisms could be primarily explained as the formation of Cd(OH)2 and CaxCd1-xCO3 solid solution on the adsorbent surface with the help of X-ray photoelectron spectroscopy.