Noncovalent immobilization of discrete molecular species on polymer supports is a unique approach to engineer multifunctional cooperative catalysts. Here we devise a modular strategy for the construction of polymersupported Cu/2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) catalytic systems by using hydrophobic interactions and aromatic stacking interactions. Polymer-supported Cu/TEMPO catalysts prepared by nanoprecipitation exhibit excellent catalytic activities for aerobic oxidation of benzyl alcohol, which can be tailored by the type of aromatic moieties, effective constituent ratios, and polymer compositions. We found that strong aromatic stacking interactions and the use of pyrene-containing polymers are crucial to enhance cooperativity. This modular strategy is promising for the immobilization of multifunctional cooperative catalysts with excellent catalytic activities and has potential for the engineering of other heterogeneous multifunctional catalysts.
The joint of high-voltage cable is the weakest part in the whole cable system, and the local defect of the middle joint will affect the distribution of the internal electric field. This paper establishes a three-dimensional model by finite element simulation software based on the electric field calculation equation in Maxwell equation system. The influence of typical defects such as impurity, scratch and air bubble on the electric field distribution in the middle joint is analysed. The results show that the internal defects of the middle joint may cause distortion of the local electric field strength in the middle joint, which may lead to deterioration of the insulation.
A simple, direct and rapid spectrophotometric method has been developed to determine the chlorhexidine digluconate content in the antimicrobial formulation. The application of first derivative spectrophotometry has managed to eliminate the interferences from other ingredients used in the complex matrices. Measurement is made at = 276.1 nm in which Beer's law is adhered in the range of 0 -50 µg/ml.
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