The purpose of the study was to evaluate the efficiency of the microwave (MW) extraction method by comparing it with a conventional method through evaluation of antimicrobial and synergism/antagonism activity of each ...The purpose of the study was to evaluate the efficiency of the microwave (MW) extraction method by comparing it with a conventional method through evaluation of antimicrobial and synergism/antagonism activity of each aquatic and ethanolic extracts samples, which were extracted from the dried plants (<em>Ficus sycomorus</em> leaves, <em>Lawsonia inermis</em> leaves and <em>Glycerrhiza glabra</em> Linn.). Nine samples of each plant for both solvents were irradiated with MW at several power outputs (180 w, 360 w, and 540 w) in several interval times (1, 2 and 3 minutes). The antibacterial activities of extracts and the synergistic effect between plants and antibiotics were evaluated using disk diffusion method against clinical isolated <em>Staphylococcus aureus</em> and <em>Escherichia coli</em>. The result revealed that the inhibition zone for more than 50% using aquatic and ethanolic samples results (extracted in two minutes and MW power 180 w) had shown the optimum extract and better antibiotic activity for each plant. Also, the results of ethanolic extracts used against selected microorganisms showed antimicrobial and synergistic effect with most antibiotics better than aquatic extracts. Our results indicate the possibility of using MW apparatus as an extractor to obtain bioactive compounds from plants and thus used in the treatment of bacterial infections, and some results of this study were encouraging. However, the antagonistic reactions of some extracts with some antibiotics and their use in combination should be further studied for<em> in vitro</em> activities. It is clearly a need to be furthermore evaluated, to identify the effective components, the mode of action and the possible toxic effect <em>in-vivo</em> of these ingredients.展开更多
The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation a...The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride (CaF2) on the vana- dium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when CaF2 is present. The leaching rate of vanadium under microwave irradiation is increased by 8%-15% when 5wt% CaF2 is added; by contrast, in the absence of CaF2, the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation, whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover, a large amount of A1 and V and a small amount of Si are dissolved from samples under microwave heating, as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When CaF2 is present, the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer, resulting in a prominent effect of mi- crowave irradiation.展开更多
文摘The purpose of the study was to evaluate the efficiency of the microwave (MW) extraction method by comparing it with a conventional method through evaluation of antimicrobial and synergism/antagonism activity of each aquatic and ethanolic extracts samples, which were extracted from the dried plants (<em>Ficus sycomorus</em> leaves, <em>Lawsonia inermis</em> leaves and <em>Glycerrhiza glabra</em> Linn.). Nine samples of each plant for both solvents were irradiated with MW at several power outputs (180 w, 360 w, and 540 w) in several interval times (1, 2 and 3 minutes). The antibacterial activities of extracts and the synergistic effect between plants and antibiotics were evaluated using disk diffusion method against clinical isolated <em>Staphylococcus aureus</em> and <em>Escherichia coli</em>. The result revealed that the inhibition zone for more than 50% using aquatic and ethanolic samples results (extracted in two minutes and MW power 180 w) had shown the optimum extract and better antibiotic activity for each plant. Also, the results of ethanolic extracts used against selected microorganisms showed antimicrobial and synergistic effect with most antibiotics better than aquatic extracts. Our results indicate the possibility of using MW apparatus as an extractor to obtain bioactive compounds from plants and thus used in the treatment of bacterial infections, and some results of this study were encouraging. However, the antagonistic reactions of some extracts with some antibiotics and their use in combination should be further studied for<em> in vitro</em> activities. It is clearly a need to be furthermore evaluated, to identify the effective components, the mode of action and the possible toxic effect <em>in-vivo</em> of these ingredients.
基金financially supported by the National Natural Science Foundation of China(Nos.51474162 and 51404174)the Research Project of the Ministry of Education of China(No.213025A)
文摘The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride (CaF2) on the vana- dium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when CaF2 is present. The leaching rate of vanadium under microwave irradiation is increased by 8%-15% when 5wt% CaF2 is added; by contrast, in the absence of CaF2, the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation, whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover, a large amount of A1 and V and a small amount of Si are dissolved from samples under microwave heating, as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When CaF2 is present, the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer, resulting in a prominent effect of mi- crowave irradiation.