RESUMEN
Al foil for high-voltage aluminum electrolytic capacitor was first D.C. etched in HCl-H2SO4 mixed acidic solution to form main tunnels and then D.C. etched in natural NaCl solution containing 0.1% H2C2O4 and different trace amounts of Zn(NO3)2. Between the two etching processes, Zn nuclei were deposited on the interior surface of the main tunnels by the natural occluded corrosion cell effect to form micro Zn-Al galvanic local cells. The effects of Zn nuclei on the cross-section etching and electrochemical behavior of Al foil were investigated using scanning electron microscopy, polarization curve measurement, and electrochemical impedance spectroscopy. The sub-branch tunnels can form along the main tunnels owing to the formation of Zn-Al micro-batteries, in which Zn is the cathode and Al is the anode. Increasing Zn(NO3)2 concentration increases the number of Zn nuclei that can serve as sites for branch tunnel initiation along the main tunnels, thereby enhancing the specific capacitance of etched Al foil.
RESUMEN
Traditional Chinese medicines (TCM)/herbal medicines (HM) are too complicated to comprehensively investigate their quality consistency effectively with a single detection technique. Hence, finding an effective, rapid, and comprehensive quality control (QC) method is of great importance for guaranteeing the safety and efficacy of TCM/HM in clinical applications. In our current research, a novel strategy of multi-wavelength fusion HPLC fingerprints and ultraviolet (UV) spectroscopic fingerprinting was proposed and successfully applied to monitor the quality consistency of compound liquorice tablets (CLT). The quality grades of 35 CLT samples from two manufacturers were successfully discriminated and evaluated by the averaged linear quantified fingerprint method (ALQFM) from a qualitative and quantitative perspective. The results showed that the UV spectroscopic fingerprints agreed well with the multi-wavelength fusion HPLC fingerprints. In addition, ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS) was applied to investigate the chemical constituents in CLT samples, providing an important chemical structural foundation for further QC and bioactivity studies. Additionally, a simple flow injection analysis (FIA) was developed to investigate the antioxidant capacity in CLT, which was based on the scavenging of 2,2-diphenyl-1-picrylhydrazyl radicals by antioxidants. Furthermore, the fingerprint-efficacy relationship between high-performance liquid chromatography (HPLC) fingerprints and the antioxidant activities of CLT samples was established utilizing orthogonal projection to latent structures (OPLS). In conclusion, this study indicated that integrating UHPLC-ESI-Q-TOF-MS/MS, UV spectroscopic fingerprints, and multi-wavelength fusion HPLC fingerprints coupled with the antioxidant activities reported could give important clues for further pharmacological and clinical studies of CLT. Meanwhile, it provides a practical strategy for the rapid screening and identifying of TCM/HM quality consistency.
