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Nano-zero-valent iron/activated carbon (nZVI/AC) composite was evaluated for its effectiveness in the stabilization of Cu, Pb, Cd, and Cr in dredged river sediment. Synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP) were adopted to compare the effects of nZVI/AC dosage, particle size, time duration, and temperature on heavy metal leachability. The results show that leachability dropped considerably with the addition of nZVI/AC and powdered particles in the size of 0.075-0.18 mm was more effective in stabilization than granular ones. Stabilization effect was stable in long-term and robust against changes in temperature. Tessier sequential extraction revealed that heavy metals were associated with solid particle, inorganic or organic matters in sediment. The addition of nZVI/AC was able to convert relatively weakly bound heavy metals into more strongly bound species and thus reduce the bioavailability and toxicity. Also, the standard potential of heavy metals may decide the mechanism of stabilization process.

This study aimed to investigate the tissue culture and rapid propagation techniques of Orostachys fimbriata, a medicinal and ornamental herbaceous perennial herb belonging to the family Crassulaceae. The leaves of O. fimbriata were used as explants to investigate the effects of plant growth regulators such as thidiazuron (TDZ), 6-benzylamino purine (6-BA) and 1-naphthaleneacetic acid (NAA), on the induction of callus, differentiation of adventitious buds and rooting of shoots. Our results showed that optimum callus induction medium was MS medium supplemented with 0.5 mg•L −1 TDZ and 0.2 mg•L −1 NAA. 1.5 mg•L −1 6-BA and 0.2 mg•L −1 NAA was the optimum hormone combination for differentiation of adventitious buds. And 0.1 mg•L −1 NAA could efficiently promote rooting. The survival rate of transplants reached about 90%. In this study, using leaves of O. fimbriata as explants, high efficient tissue culture and regeneration system of O. fimbriata were established, and the period from leave to transplant plantlet was about 3 months. The presently developed protocol could be used for large scale clonal propagation and germplasm conservation of O. fimbriata. The efficient tissue culture system of O. fimbriata would provide technical support for its utilization.

Background Tangzhiqing (TZQ), as a potential α-glycosidase inhibitor, possesses postprandial hypoglycaemic effects on maltose in humans. The aim of this study was to investigate the mechanisms by which TZQ attenuates postprandial glucose by interrupting the activity of maltase, including inhibitory kinetics and circular dichroism studies. Methods In this study, we determined the inhibitory effect of TZQ on maltase by kinetic analysis to determine the IC50 value and enzyme velocity studies and line weaver-burk plot generation to determine inhibition type. Acarbose was chosen as a standard control drug. After the interaction with TZQ and maltase, secondary structure analysis was conducted with a circular dichroism method. Results TZQ showed notable inhibition activity on maltase in a reversible and competitive manner with an IC50 value of 1.67 ± 0.09 μg/ml, which was weaker than that of acarbose (IC50 = 0.29 ± 0.01 μg/ml). The circular dichroism spectrum demonstrated that the binding of TZQ to maltase changed the conformation of maltase and varied with the concentration of TZQ in terms of the disappearance of β-sheets and an increase in the α-helix content of the enzyme, similar to acarbose. Conclusions This work provides useful information for the inhibitory effect of TZQ on maltase. TZQ has the potential to be an α-glycosidase inhibitor for the prevention and treatment of prediabetes or mild diabetes mellitus.