'Fengjiewancheng' (FW) (Citrus sinensis), a bud sport of 'Fengjie 72-1' navel orange (FJ), ripens one month later than its parental line. Differences in sugar and acid content and the transcript level of sucrose-and citric-metabolic enzymes for the two cultivars were investigated during fruit ripening. Results showed that both sugar and acid metabolisms of the mutant were affected by the mutation. In the pulp of FW, sugar content was significantly lower than that in FJ before 227 DAF (days after flowering) and higher at 263 DAF; the mutant's gene expression of one isoform of citrus sucrose synthase (CitSS1) was delayed, and its gene expression of citrus acid invertase (CitAI) was stronger than that in its parental cultivars at 207 and 263 DAF. In the peel, only the sucrose content in FW was significantly lower than those in FJ at the early periods of fruit ripening (165 and 187 DAF); however the transcripts of the sucrose-cleaving enzymes in the mutant were higher than those in FJ at different ripening points. As regards acid accumulation in the two cultivars, it was observed that in the pulp of the mutant, the malic acid content was significantly lower than that in its parental cultivars from 187 to 263 DAF, and in the peel, remarkably higher during the whole fruit ripening period. The citric acid content in both the pulp and the peel of FW was higher than that in those of FJ during the early ripening period and lower during the late ripening period, which were correspondingly associated in part with the higher transcript level of citrus mitochondrial citrate synthase (CitCS) and with lower or undetectable transcript level of citrus cytosolic aconitase (CitAC). Hence, it could be concluded that the mutation in FW affected sugar and acid metabolism, which might be related with other late-ripening phenotypes.
In this study, the pyrolysis behaviour of nonmetal fraction of waste printed circuit boards (NMF-WPCBs) was studied based on five model-free methods and distributed activation energy model (DAEM). The possible decomposition mechanism was further probed using the Criado method. Thermogravimetric analysis indicated that the NMF-WPCBs pyrolysis process could be divided into three stages with temperatures of 37–330°C, 330–380°C and 380–1000°C. The mass loss at different heating rate was determined as 26.85–29.98%, 13.47–24.21% and 20.43–23.36% for these stages, respectively. The activation energy ( Eα) from various model-free methods first increased with degree of conversion ( α) increasing from 0.05 to 0.275, and then decreased beyond this range. The coefficient ( R) from the Flynn–Wall–Ozawa (FWO) method was higher, and the resulting Eα fell into the range of 214.947–565.660 kJ mol−1. For the DAEM method, the average Eα value was determined as 337.044 kJ mol−1, comparable with 329.664 kJ mol−1 from the FWO method. The thermal decomposition kinetics of NMF-WPCBs could be better described by the second-order reaction.
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