Characterization of keto-enol tautomerism of p -hydroxyphenylpyruvic acid using CE with amperometric detection and spectrometric analysis

Microbial Dynamics and Pathogen Control During Fermentation of Distiller Grains: Effects of Fermentation Time on Feed Safety

Determining the effects of fermentation duration on the microbial ecosystem, potential pathogenic risks, and metabolite generation during the fermentation of distilled grains is essential for safeguarding the safety and enhancing the nutritional profile of animal feed. This study investigates the effect of varying fermentation times (9, 30, and 60 days) on microbial diversity, pathogenic risk, and metabolite profiles in distiller grains using 16S rDNA sequencing and LC-MS-based metabolomics. The results showed that early fermentation (9-30 days) enhanced the abundance of beneficial bacteria, such as Lactobacillus reuteri and Lactobacillus pontis (p < 0.05), while pathogenic bacteria, like Serratia marcescens and Citrobacter freundii, were significantly reduced (p < 0.05). Metabolomic analysis revealed an increase in unsaturated fatty acids and the degradation of biogenic amines during early fermentation. However, prolonged fermentation (60 days) led to a resurgence of pathogenic bacteria and reduced the synthesis of essential metabolites. These findings suggest that fermentation duration must be optimized to balance microbial safety and nutrient quality, with 30 days being the optimal period to reduce pathogenic risks and enhance feed quality.

Proton transfer in the benzimidazolone and benzimidazolthione tautomerism process catalyzed by polar protic solvents

The tautomeric equilibrium of benzimidazolone and benzimidazolthione have been studied by the density functional theory method using the CAM-B3LYP functional together with the 6-311G(d,p) basis set. Two separate mechanisms have been investigated: a direct intramolecular transfer using the polarizable continuum model and an indirect proton transfer assisted by a molecule of solvent (C6H12, H2O, CH3OH, and H2O2). In both cases, the results obtained indicate that ketone and thione are the most stable forms. However, the enhanced height of the activation barrier for the four-center mechanisms describing the tautomerism reaction as a direct intramolecular transfer implicates a relatively disadvantaged process. The participation of a polar protic solvent molecule allows the lowering of the activation energy barrier. Potential energy profiles of keto-enol and thio-enol tautomerism assisted by methanol and water are very different. The former one describes a concerted mechanism but the latter does not because it is associated with asynchronous processes that take place during the thio-enol tautomerism.

Unusual H/D isotope effect in isomerization and keto–enol tautomerism reactions of pyruvic acid: nuclear quantum effect restricts some rotational isomerization reactions

H/D isotope effects on isomerization and keto–enol tautomerism reactions of the pyruvic acid molecule have been investigated using the multicomponent B3LYP methods, which can take account of the nuclear quantum effect of protons and deuterons.

Recent progress for capillary electrophoresis with electrochemical detection

Capillary electrophoresis (CE) is an attractive technique in separation science because of its high separation performance, short analysis time and low cost. Electrochemical detection (EC) is a powerful tool for CE because of its high sensitivity. In this review, developments of CE-EC from 2008 to August, 2011 are reviewed. We choose papers of innovative and novel results to demonstrate the newest and most important progress in CE-EC.