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In this study, tri-butyl-phosphate (TBP)-kerosene is used as the extraction solvent to remove phenols from coal gasification wastewater, and the complex mechanism of the extraction is investigated. An effect experiment is conducted to determine the complex structures, the enthalpy change of reaction, and the effect of extraction solvent concentration and temperature on the distribution coefficient. To predict the extraction effect before the experiment, the distribution coefficient mathematical model of phenol extraction is established, which is based on a liquid-liquid extraction model and verified for accuracy by the experiment. The effect experiment result shows that with an increase in concentration of TBP and decrease in temperature, the extraction distribution coefficient increases and further determines the complex structures and the enthalpy change of the reaction. Meanwhile, a comparison of experimental and calculated values in the model experiment result shows that the average relative error of extraction distribution coefficient is 5.56% in different concentrations of TBP and 2.72% in different temperatures. Considering the error of the experiment, this work concludes that the distribution coefficient mathematical model of phenol extraction has a high predictive effect on the distribution coefficient and extraction rate of volatile phenol in actual wastewater.
We investigated rice husk as the sole carbon source as well as biofilm carrier in the biological denitrification of wastewater in up-flow laboratory reactors. Fast startup of the reactor and high nitrate removal efficiency was observed. The highest denitrification rate (about 0.096kg/m³·d) was achieved when flow rate and nitrate concentration were 41.4L/d and 25.0mg/L, respectively. Flow rate and nitrate concentration of the influent were observed to have a significant effect on nitrate removal efficiency. The reactor had the ability to accommodate a wide range of pH (6.5-8.5) and DO (1.5-4mg/L). A time-dependent decrease in nitrate removal efficiency was observed after 72 days of operation. And the addition of new rice husk brought about a rapid increase of nitrate removal efficiency. Results showed that rice husks can be an economical and effective carbon source for the nitrate removal process.
Mitochondrial uncoupling proteins play important roles in generation of metabolic thermogenesis, response to stress situations, and regulation of energy metabolism. We demonstrated here that the absence of LeUCP in tomato inhibited photosynthesis using virusinduced gene-silencing approach. A significant decrease in the rate of CO2 assimilation in LeUCP-silencing plants was observed over a range of different light intensities. Absence of LeUCP resulted in lower net photosynthetic rate, lightsaturated rate of the CO2 assimilation (Asat), maximum carboxylation rates (Vcmax) and maximum RuBP regeneration rate (Jmax). Activities of ribulose-1,5-bisphosphate carboxylase/oxygenase Rubisco and stromal fructose-1,6- bisphosphatase and genes expression levels encoded Calvin cycle enzymes of LeUCP gene-silencing plants were inhibited. However, silencing of LeUCP gene had no effect on Fv/Fm, but decreased photochemical quenching and electron transport rate. Meanwhile, non-photochemical quenching and Je (PSII), the distribution of Je (PCR) and Je (PCO), the content of AsA, NAD, and the ratios of NAD?/ NADH, AsA/DHA were significantly reduced with increased reactive oxygen species while GSH and GSSG were unaltered. Taken together, these results strongly suggest that LeUCP gene in tomato leaves is crucial in maintaining the redox poise of the mitochondrial electron transport chain to facilitate photosynthetic metabolism.
This study investigated the effect of saponins gypenoside (gynosaponins) on methane production and microbe numbers in a co-culture of a fungus, Piromyces sp. F1, and a methanogen, Methanobrevibacter sp.. Two co-culture systems were used: with methanogen (co-culture I) and without methanogen (co-culture II; methanogen growth inhibited by chloramphenicol). Each co-culture system was treated with 0, 50, 100 or 200 mg gynosaponins/l culture medium. Gas production, methane concentration and volatile fatty acid concentration (VFA) were measured for each treatment group. The numbers of anaerobic fungi and methanogen were quantified by real time PCR. The results showed that, compared with the control, gynosaponin significantly reduced the gas production, methane concentration, methane to TVFA ratio (total volatile fatty acid), TVFA concentration, number of fungi (except for 50 mg dose of gynosaponin in co-culture I) and number of methanogens. Methane was not detected in co-culture II. The individual VFAs proportion of TVFA were not affected by gynosaponins in either of the co-cultures. The pH was higher in both co-cultures than that of the control (P<0.01). These data suggest that gynosaponins has the potential for being used as feed additive to modulate the ruminal fermentation, inhibit the methanogen growth and reduce methane production.
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