Preparation and identification of antioxidant peptides from Quasipaa spinosa skin through two-step enzymatic hydrolysis and molecular simulation.

Frog skin, a by-product of Quasipaa Spinosa farming, is rich in protein and potentially a valuable raw material for obtaining antioxidant peptides. This study used papain combined with acid protease to digest frog skin in a two-step enzymatic hydrolysis method. Based on a single factor and response surface experiments, experimental conditions were optimized, and the degree of hydrolysis was 30 %. A frog skin hydrolysate (QSPH-Ⅰ-3) was obtained following ultrafiltration and gel filtration chromatography. IC50 for DPPH, ABTS, and hydroxyl radical scavenging capacities were 1.68 ± 0.05, 1.20 ± 0.14 and 1.55 ± 0.11 mg/mL, respectively. Peptide sequences (17) were analyzed and, through molecular docking, peptides with low binding energies for KEAP1 were identified, which might affect the NRF2-KEAP1 pathway. These findings suggest protein hydrolysates and antioxidant peptide derivatives might be used in functional foods.

Factors affecting user satisfaction with new energy vehicles: A field survey in Shanghai and Nanjing.

Based on the diffusion of innovation theory (DOI), this paper aims to explore the potential factors that influence user satisfaction with new energy vehicles (NEVs). Furthermore, we introduce the term "personal environmental awareness" (PEA) and attempt to examine its contingent effects. A moderated hierarchical linear regression analysis (MHLRA) method is conducted to analyze the data collected from a field survey of 335 early-drivers of NEVs. Empirical results show that experiences related to usefulness, experience of ease-of-use, total cost, driving range, and infrastructure readiness are important factors that influence user satisfaction with NEVs. In the case of moderating effects, we found that PEA might strengthen the positive effects of experienced usefulness, experienced ease-of-use, driving range, and infrastructure readiness in terms of user satisfaction with NEVs. However, the moderating role of PEA in the relationship between total cost and user satisfaction is not statistically significant. Our research findings might provide some useful insights for market managers, academic researchers and policy makers.