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Drought loss risk curves can quantitatively assess regional drought and indicate the mechanism of drought hazards. In this study, the drought events were identified using the run theory based on Standard Precipitation Index (SPI) and Composite meteorological drought Index (CI) separately calculated by daily weather data during 1955–2012. The frequency of drought events was calculated by using the Copula function. The yield loss of soybeans under different irrigation levels in dry years was simulated by DSSAT-CROPGRO-soybean model. Finally, the regional drought risk for soybeans in Bengbu city was analyzed by constructing a series of relationship curves among the drought frequency, soybean drought loss, and the irrigation level. The results indicated that (1) both the SPI and CI were applicable to identifying drought events in the selected city, but SPI was more sensitive in identifying short-term drought events, and CI was more reliable in recognizing medium-term drought events. (2) The frequency of drought events during the target crop's growing period and the corresponding yield loss rate satisfied the semi-logarithmic function, and the average values of their determinant coefficients were 0.68 and 0.74 based on SPI and CI, respectively. (3) Irrigation could significantly reduce soybean yield loss in non-extreme drought events. Therefore, drought loss risk curves can reflect regional drought risk more quantitatively and facilitate the assessment and management of regional drought risk.

It is significant to develop new sorbents with high affinity and good selectivity for uranium extraction from aqueous solution. We herein developed a new type of sorbent based on SBA-15 with covalently attached positive charge and phosphate group for uranium extraction. High selectivity and fast kinetics for uranium (VI) sorption can be achieved by the functional material, which may be originated from the cooperative effect of positive charges: the negative uranium complex would be attracted by electrostatic interaction, while the other metal cations were repelled. The functional materials could be efficiently regenerated and reused with high sorption efficiency after five cycles. This work may provide a new approach for efficient sorption of uranium from aqueous solution.

It is significant for environment and human health to develop new materials for the sorption of radioactive technetium. We report herein a novel method to synthesize surface ion-imprinted magnetic microspheres for efficient capture of technetium ions. Specifically, perrhenate anion as the structural surrogate for pertechnetate anion, was employed as template to prepare ion-imprinted magnetic microsphere by “one-pot” radical polymerization and quaternization. The sorption behavior is closely related with the surface chemical composition: the more nitrogen content, the higher sorption efficiency. The sorption is an exothermic spontaneous sorption process and kinetically followed pseudo-second-order model. A sorption capacity of 62.8 mg of Re/g could be achieved at 298.15 K and pH = 6. Compared with non-imprinted composites, imprinted microspheres showed higher selectivity, faster kinetics, and larger sorption capacity of perrhenate ions. This work may provide a promising approach for the efficient sorption of pertechnetate.

Interaction between peptide and lipid membrane plays a major role in biological activity of membrane-active peptide. We describe here a new biocompatible polymeric assembly to support membrane peptide. Specifically, chitosan-graft-poly(sulfobetaine methacrylate) (CS-g-PSBMA) was synthesized for alamethicin assembly by controlled polymerization under γ-ray irradiation. The graft copolymer could self-assemble into micelles in distilled water for supporting alamethicin. The assembly of alamethicin with CS-g-PSBMA micelles in aqueous solutions was related with the ratio of alamethicin/CS-g-PSBMA: the more alamethicin, the smaller sizes of the hybrid complex. Moreover, alamethicin penetrated into the hydrophobic cores of CS-g-PSBMA micelles while displayed secondary helical conformation in the complex. The results indicate that CS-g-PSBMA assemblies can be used to support membrane peptide.

The colloidal particles with switchable surfaces (i.e. smart surfaces) have attracted great attention for numerous potential industrial applications. We report here a novel approach for the fabrication of polymeric particles with smart surfaces by emulsion polymerization using “giant” surfactant. Specifically, the “giant” surfactant was obtained by incorporating poly(4-vinylpyridine) chains onto the one bulb of snowman-shaped polystyrene particles, and then used as emulsifier for the emulsion polymerization at pH = 2.00. The nearly monodisperse waxberry-like polystyrene particles were prepared with dual-size roughness surfaces, and the particulate film exhibited reversibly pH-switchable superhydrophobic property due to the pH-sensitivity of P4VP chains and the surface topology. This property enabled the particles could be used to effectively sequester hazardous anions from the wastewater.

We report a novel chitosan derivative, chitosan-ionic liquid (CS-IL) conjugation for anion adsorption. Specifically, CS-IL conjugation was synthesized through the reaction of amino groups of chitosan with carboxylic groups of 1-carboxybutyl-3-methylimidazolium chloride. Due to the amphiphilic structure, CS-IL conjugation could self-assemble into nanoparticles in distilled water. This novel chitosan derivative revealed good anion adsorption performance, and the adsorption capacity of Cr2O7(2-) and PF6(-) was 0.422 mmol/g and 0.840 mmol/g, respectively. The adsorption of Cr2O7(2-) and PF6(-) could be improved at low pH, which was ascribed to the adsorption of protonated NH2 on chitosan. Importantly, the chitosan derivative would aggregate in the water after the adsorption and could be easily separated. The properties enable CS-IL conjugation to be used as a novel anion adsorbent for wastewater treatment.