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For nanostores, striving to become the community group-buying leader is gaining prominence. This paper aims to construct Hotelling linear models to investigate whether nanostores should be registered as leaders and their decisions in a competitive environment.

This paper constructs three Hotelling linear models: neither nanostore registers as community leader, only one nanostore registers as community leader and both nanostores register as community leader. The competitive operation strategies of two general nanostores under three scenarios are solved.

The study finds that nanostores without a cost advantage may benefit from being the first leader. The nanostore's preferred decisions depend on the investment cost parameters of its own and competitors which may lead to market share competition. Furthermore, consumers' sensitivity to community group-buying service has a negative effect on nanostores' profit.

The study is one of the few to consider the competition between community leaders. Besides, the study considers that the utilities functions of consumers are concurrently impacted by the service decisions, along with the price in different nanostores. It can provide nanostores useful implications in the dynamic industry.

This study aims to prepare an imprinted composite membrane with grafted temperature-sensitive blocks for the efficient adsorption and separation of rhenium(Re) from aqueous solutions.

PVDF resin membrane was used as the substrate, dopamine and chitosan (CS) were used to modify the membrane surface and temperature-sensitive block PDEA was grafted on the membrane surface. Then acrylic acid (AA) and N-methylol acrylamide (N-MAM) were used as the functional monomers, ethyleneglycol dimethacrylate (EGDMA) as the cross-linker and ascorbic acid-hydrogen peroxide (Vc-H₂O₂) as the initiator to obtain the temperature-sensitive ReO4⁻ imprinted composite membranes.

The effect of the preparation process on the performance of CS–Re–TIICM was investigated in detail, and the optimal preparation conditions were as follows: the molar ratios of AA–NH₄ReO₄, N-MAM and EGDMA were 0.13, 0.60 and 1.00, respectively. The optimal temperature and time of the reaction were 40 °C and 24 h. The maximum adsorption capacity of CS–Re–TIICM prepared under optimal conditions was 0.1071 mmol/g, and the separation was 3.90 when MnO4⁻ was used as the interfering ion. The quasi first-order kinetics model and Langmuir model were more suitable to describe the adsorption process.

With the increasing demand for Re, the recovery of Re from Re-containing secondary resources becomes important. This study demonstrated a new material that could be separated and recovered Re in a complex environment, which could effectively alleviate the conflict between the supply and demand of Re.

This contribution provided a new material for the selective separation and purification of ReO4⁻, and the adsorption capacity and separation of CS–Re–TIICM were increased with 1.673 times and 1.219 time compared with other Re adsorbents, respectively. In addition, when it was used for the purification of NH₄ReO₄ crude, the purity was increased from 91.950% to 99.999%.