Lignin is the world's greatest renewable aromatic biofeedstock, and it has promising applications in high value-added chemical products. Herein, N-Co/ATP-CZO was used as a catalyst for the depolymerization of alkali lignin in ethanol and isopropanol systems, and explored the effects of formic acid (FA) amount, reaction time, reaction temperature and other factors on the depolymerization of alkali lignin. Among them, formic acid serves as both catalytic and in situ-hydrogen donor. Ultimately, the highest yield of bio-oil (59.28% (mass)), including 30.05% (mass) of monomer , was obtained after a reaction of FA to alkali lignin mass ratio of 4 and 240 °C for 8 h. Among the monomers, the yield of Guaiacol was the highest (5.94% (mass)), followed by 2-methoxy-4-methylphenol (5.74% (mass)). This study, the modification of attapulgite was carried out to reduce the acidity while enhancing the catalytic activity for depolymerization, and the selection of hydrogen donor was investigated. A feasible pathway for lignin depolymerization research was opened.
Glucagon-like peptide-1 (GLP-1) is a natural incretin hormone released from intestinal L-cells in response to hormonal, neural and nutrient stimuli. Liraglutide is derived from human GLP-1 by substituting Lys34 with Arg and conjugating a palmitic acid to Lys26 via a glutamate spacer, which has a long-lasting hypoglycemic effect. The precursor of liraglutide is a K34R mutant of GLP-1 (GLP-1 R34 ) and was produced previously by either yeast protein expression system or peptide solid phase synthesis. However, degradation of secreted proteins limits the effectiveness of yeast protein expression system and peptide solid phase synthesis requires the use of large amounts of organic solvents and expensive condensation agents. In this study, we reported a novel method to prepare GLP-1 R34 using E. coli protein expression system. The GLP-1 R34 peptide was overexpressed as an MFH-GLP-1 R34 fusion protein and was released from the fusion protein through formic acid cleavage. The target peptide was purified by reverse-phase chromatography and ion exchange chromatography. Our work demonstrated a high-productive process for large-scale preparation of the liraglutide precursor with high purity.
To explore nanocatalysts with high electro-catalytic performance and less loading of precious metals, efforts have been made to develop electrochemical methods with high spatial resolution at the single nanoparticle level. Herein, a highly sensitive single-nanoparticle coulometry method is successfully developed to study the electrochemical activity and oscillation of single PtTe nanocatalysts. Based on microbattery reactions involving the formic acid electro-oxidation and the deposition of Ag on the single PtTe nanocatalyst surface, this method enables the transition from the undetectable sub-fA electric signal of the formic acid electro-oxidation into strong localized surface plasmon resonance scattering signal of Ag detected by dark-field microscopy. The lowest limiting current for a single nanocatalyst is found to be as low as 25.8 aA. Different trends of activity versus the formic acid concentration and types of activity of the single nanocatalyst have been discovered. Unveiled frequency-amplitude graph shows that the two electrochemical oscillation modes of low frequency with high amplitude and vice versa coexist in a single PtTe nanocatalyst, indicating the abundantly smooth surfaces and defects of nanocatalysts. This conducted study will open up the new avenue for further behavioral and mechanistic investigation of more types of nanocatalysts in the electrochemistry community.
危险品化学品经营许可证（带存储）