RÉSUMÉ
Phosphonate-based nerve agents, as a kind of deadly chemical warfare agent, are a persistent and evolving threat to humanity. Zirconium-based metal-organic frameworks (Zr-MOFs) are a kind of highly porous crystalline material that includes Zr-OH-Zr sites and imitates the active sites of the phosphotriesterase enzyme, representing significant potential for the adsorption and catalytic hydrolysis of phosphonate-based nerve agents. In this work, we present a new Zr-MOF, UiO-66-2I, which attaches two iodine atoms in the micropore of the MOF and exhibits excellent catalytic activity on the degradation of a nerve agent simulant, dimethyl 4-nitrophenyl phosphate (DMNP), as the result of the formation of halogen bonds between the phosphate ester bonds and iodine groups. Furthermore, various morphologies of UiO-66-2I, such as blocky-shaped nanoparticles (NPs), two-dimensional (2D) nanosheets, hexahedral NPs, stick-like NPs, colloidal microspheres, and colloidal NPs, have been obtained by adding acetic acid (AA), formic acid (FA), propionic acid (PA), valeric acid (VA), benzoic acid (BA), and trifluoroacetic acid (TFA) as modulators, respectively, and show different catalytic hydrolysis activities. Specifically, the catalytic activities follow the trend UiO-66-2I-FA (t1/2 = 1 min) > UiO-66-2I-AA-NP (t1/2 = 4 min) ≈ UiO-66-2I-VA (t1/2 = 4 min) > UiO-66-2I-BA (t1/2 = 5 min) > UiO-66-2I-PA (t1/2 = 15 min) > UiO-66-2I-TFA (t1/2 = 18 min). The experimental results show that the catalytic hydrolysis activity of Zr-MOF is regulated by the crystallinity, defect quantity, morphologies, and hydrophilicity of these samples, which synergistically affect the accessibility of catalytic sites and the diffusion of phosphate in the pores of Zr-MOFs.
RÉSUMÉ
The quality of fresh-cut produce, particularly sweet potatoes, is crucial for their value. Licorice extract is an optional additive in fresh-cut sweet potatoes. This study examined the impact of three licorice extracts (licorice acid, LA; licorice flavonoids, LF; and licorice polysaccharides, LP) on the quality of fresh-cut sweet potato slices (FCSPSs) for one week of storage. After one week of storage, the extracts showed varying effects on FCSPSs. LA and LF treatments reduced the area proportion of browning (APB), while LP treatments increased APB and decreased L* values. Antioxidant experiments revealed that LP treatments increased PPO and POD activity while reducing SOD activity. The concentrations of the three licorice extracts showed a strong negative correlation with SOD activity. In conclusion, LP harmed the appearance and antioxidant qualities of FCSPSs. LA and LF may be suitable additive components for FCSPSs, and 30 mg/mL LA and LF treatments were found to maintain the appearance and texture quality of FCSPSs during storage. Therefore, careful consideration should be given when using LP as a food additive for FCSPSs.