RESUMO
A clustered countercurrent-flow micro-channel reactor (C-CFMCR) with adjustable magnification times was constructed for the preparation of KMnF3 perovskite fluoride by a co-precipitation process, in which the concentrations and feed rates of reactants were precisely controlled. Benefitting from the enhanced micromixing efficiency of the microreactor, the KMnF3 particles prepared in C-CFMCR were smaller and less aggregated than those produced with traditional stirred reactors (STR). The prepared KMnF3 was applied as the electrode material in supercapacitors, and the electrochemical measurements showed that the KMnF3 obtained under optimal conditions had a discharge specific capacitance of â¼442 F g-1 at a current density of 1 A g-1, with a decline of â¼5.4% after 5000 charge-discharge cycles in an aqueous electrolyte of 2 M KOH. It was also found that the morphologies and electrochemical performances of the prepared KMnF3 particles changed accordingly with the micromixing efficiencies of C-CFMCR, which can be adjusted by the reactor structure and operating conditions. An asymmetric supercapacitor assembled with the KMnF3 and activated carbon exhibited an energy density of 13.1 W h kg-1 at a power density of 386.3 W kg-1, with eminent capacitance retention of â¼81.2% after 5000 cycles. In addition, only a slight amplification effect of C-CFMCR on the co-precipitation process was noticed, indicating that the C-CFMCR is a promising technology for the massive and controllable production of KMnF3 particles as well as other ultrafine particles.
RESUMO
A clustered countercurrent-flow micro-channel reactor (C-CFMCR) has been assembled by the numbering-up of its single counterpart (S-CFMCR). Its micromixing performance was then studied experimentally using a competitive parallel reaction system, and the micromixing time was calculated as the micromixing performance index. It was found that the micromixing time of C-CFMCR was ranged from 0.34 to 10 ms according to its numbering-up times and the operating conditions of the reactor, and it was close to that of S-CFMCR under the same operating conditions, demonstrating a weak scaling-up effect from S-CFMCR to C-CFMCR. The C-CFMCR was then applied to prepare ultrafine manganese dioxide in a continuous manner at varying micromixing time. It showed that the micromixing time had a major effect on the particle structure. More uniform and smaller MnO2 particles were obtained with intensified micromixing. By building a typical three electrode system to characterize their performance as a supercapacitor material, the MnO2 particles prepared by both S-CFMCR and C-CFMCR under optimal conditions displayed a specific capacitance of ~175 F·g-1 at the current density of 1 A·g-1, with a decline of ~10% after 500 charge-discharge cycles. This work showed that C-CFMCR will have a great potential for the continuous and large-scale preparation of ultrafine particles.
RESUMO
Soy isoflavones exhibit various biological activities, such as antioxidant, anti-tumor, anti-inflammatory, and cardiovascular protective effects. The present study was designed to investigate the effects of sixteen synthesized 3-amino-2-hydroxypropoxy genistein derivatives on cell proliferation and activation of Nrf2 (Nuclear factor erythroid 2-related factor 2)/ARE (antioxidant response elements) pathway in human cancer cell lines. Most of the tested compounds exerted greater cytotoxic activity than genistein, as measured by MTT assay. Moreover, compound 8c showed the highest ARE-luciferase reporter activity among the test compounds. It strongly promoted Nrf2 nuclear translocation and up-regulated the expression of total Nrf2 and downstream targets NQO-1 and HO-1 at protein level. The present study may provide a basis for the application of isoflavone derivatives as Nrf2/ARE pathway inducers for cancer therapy and cancer prevention.
