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The durability and heavy metal leaching behavior of red mud-class F fly ash based geopolymers (RFFG) were investigated in this study. RFFG specimens were soaked in sulfuric acid solutions (pH = 3.0) and deionized water (pH = 7.0) for 1-120 days, and then their remaining mechanical properties and the change in the microstructures were characterized with unconfined compression tests, three-point bending tests, scanning electron microscopy, X-ray diffractometer and Fourier transform infrared spectroscopy, respectively. The leaching behavior of heavy metals in RFFG samples after soaking up to 14 days was also examined with atomic absorption spectroscopy. The RFFG samples' resistance against sulfuric acid was comparable to the ordinary Portland cement (OPC), and their mechanical degradation was mainly attributed to the depolymerization and dealumination of geopolymer gels. The highest concentrations of the heavy metals leached by the sulfuric acid from the RFFG samples were much lower than the respective US EPA limits for soil contamination.

The modified novolac epoxy resins with furan pendant groups were prepared by novolac epoxy resin and furfuryl alcohol and then crosslinked by bifunctional maleimide via Diels-Alder (DA) chemistry to obtain the thermally reversible and self-healing novolac epoxy resins. The as-prepared crosslinked novolac epoxy resins were characterized by FT-IR, NMR, TGA, and DMA. The results indicate that the novel crosslinked novolac epoxy resins present higher storage modulus (2.37 GPa at 30 C) and excellent thermal stability (348 C at 5% mass loss). Furthermore, the thermal reversible and self-healing properties were studied in detail by DSC, SEM, thermal re-solution, and gel-solution-gel transition experiments. All the results reveal that the crosslinked novolac epoxy resins based on DA reaction can be used as smart material for the practical application of electronic packaging and structural materials.

The asymmetric synthesis of enantiomerically pure α-aminophosphonates with high and bioselective activities is a challenge. Here, we report that both enantiomers of α-aminophosphonates bearing the N-benzothiazole moiety can be prepared in high yields (up to 99%) and excellent enantioselectivities (up to 99% ee) by using chiral thiourea organocatalysts. Evaluation of the antiviral activities of our reaction products against cucumber mosaic virus (CMV) led to promising hits with high and selective biological activities, wherein (R)-enantiomers exhibit higher biological activities than the corresponding (S)-enantiomers. Especially, compound (R)-3b with excellent anti-CMV activity (curative activity, 72.3%; protection activity, 56.9%; and inactivation activity, 96.9%) at 500 μg/mL emerged as a potential inhibitor of the plant virus. The difference in the selective bioactivity could be affected by the combination mode of the three-dimensional space between the enantiomers of α-aminophosphonate and cucumber mosaic virus coat protein (CMV-CP) via florescence spectroscopy and molecular docking.