Regulation of Tetramethylpyrazine Formation by the Phenolics-Fenton Coupled Redox Cycling System.

A novel technique for generating tetramethylpyrazine (TTMP) was proposed, carried out on a phenolics-Fenton coupled redox cycling system in an acetoin-ammonium acetate (AA-ACT) pattern reaction. The TTMP generation employing the Fenton system is a first-order reaction that significantly increased the reaction rate, especially in the early stages, distinguishing it from the original zero-order kinetics reaction pattern. Further, the Fenton reaction effectively promotes the TTMP generation at lower temperature, and epigallocatechin gallate (EGCG) could reset the Fenton reaction, accomplishing the redox cycle. We have discovered a novel class of intermediate products, N-substituted amides, which act as a "reservoir" and transform into amino acid, then undergo aromatization to generate TTMP. The results provide a useful supplement for intelligent synthesis route design, and a new approach for understanding the transformation pathways of pyrazines.

Effect of jet airflow deflection on cleaning performance of filter cartridge.

Pleated cartridge filters are widely used to remove dust in industrial processes. However, pulse-jet cleaning is not uniform on the filter cartridges. The phenomenon of pulsed jet airflow deflection exists during pulse jet cleaning, which causes a large impact on the local area of filter cartridge and shortens the service life of the filter cartridge. But perhaps due to the lack of effective testing methods, the impact of pulsed jet deflection on dust cleaning is often ignored. Under more comprehensive conditions, such as jet pressures, jet distance, and jet-hole diameter, the influence of the pulsed jet airflow deflection on the cleaning performance of the filter cartridge has been discussed systematically, by testing the peak static pressure on the side wall of the filter cartridge. The experimental results show that the sidewall peak static pressure of the face-flow surface of the filter cartridge is greater than that of the back-flow surface due to deflection, and the difference between the two is proportional to the jet-hole diameter and jet pressure. After installing the diversion nozzle, the results show that the peak static pressures of the face-flow and back-flow surfaces are basically the same. Therefore, it is proved that the diversion nozzle can effectively correct the jet airflow deflection.