Chemical and biological investigation of green tea has been generally performed while using different infusions that are prepared without consideration of the effects of sample preparation conditions. In this study, for the first time, the effects of green tea brewing conditions on the antioxidant activity and chemical profiles of metabolome and catechin compounds were examined at 60 °C and 95 °C for a period of 5–300 min. The antioxidant capacities of the tea infusions, which were assessed as per 2,2-diphenyl-1-picryl-hydrazyl hydrate (DPPH) radical scavenging activity, depended more on temperature than time. Metabolomics study that was based on ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF/MS) revealed that the metabolic profiles, including 33 differential metabolites, were significantly changed by temperature and time, with the effects of time being more evident at 95 °C starting after 30 min. Infusions that were brewed at 95 °C for greater than 30 min yielded distinct profiles in the hierarchical clustering analysis. The quantification of eight catechins by UHPLC-QqQ/MS showed that the total catechin level peaked at 95 °C brewing at 10 min, after which the levels of four epi-forms of catechins decreased and those of four non-epi-forms increased, implying the epimerization of catechins over time. These results suggest that the brewing conditions for sample preparation of green tea should be put into careful consideration in studies where green tea extracts are applied as aqueous infusions.
This paper studies the modification of petroleum asphalt with enzymatic hydrolysis lignin (EHL) epoxy resin. EHL epoxy resin was successfully synthesized by EHL, a novel eco-material with high chemical reactivity. Different amounts of EHL epoxy resin were compounded into AH-70 paving asphalt. The effect of EHL epoxy resin on modified asphalt was examined by penetration, soften point, thin film oven test (TFOT), ductilily tests. The results showed that EHL epoxy resin had marked effect on the high-temperatrue property of increasing softening point at the content of 2-9wt% and it had significantly effect on the low-temperature properties and aging resistance with EHL epoxy resin content of 2-9wt% in modified asphalts. TG analysis indicated that EHL epoxy resin had the high mass loss temperature than pure asphalt. Anti-aging property of asphalt was improved by compounding EHL epoxy resin with asphalt.
Fire extinguishing with the superior performance of fly ash composite colloid material is a cost-effective colloid fire prevention technology. In this paper, a new powder additive (suspending agent (XK-XJ) and gelling agent) was developed for the existing fire extinguishing technology of fly ash compound colloid. Tests show that the best additions to the fly ash slurry were 0.3% and 0.1∼0.3%, respectively. The grouting technical scheme of adding a suspending agent on the ground and gelling agent downhole was proposed to solve the problems of solid material settlement and blockage in the long-distance pipeline transportation process. Finally, the optimized fly ash colloid fire prevention and extinguishing technology was successfully applied to the fire control engineering examples of close-range coal seam groups, and the rationality of the developed powder and its proportion was tested, and the feasibility in coal fire control was tested.
In this paper, a series of enzymatic hydrolysis lignin modified petroleum asphalts were prepared. The physical properties such as softening point, ductility at low temperature and penetration of the modified asphalt were investigated. The penetration index of asphalt modified with EHL was higher than that of unmodified asphalt, equivalent softening point increased and equivalent brittle point decreased with the increase of EHL amount, which showed that the addition of EHL was favorable to reduce the temperature susceptivity of asphalt. When the EHL was 4%, the ductility was 39.0 cm. Meanwhile, low temperature performance of asphalt could be further improved by adding EHL and a small amount of SBS.
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