- Characterization of initial reaction intermediates in heated model systems of glucose, glutathione, and aliphatic aldehydes
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To understand the effect of lipid degradation on Maillard formation of meaty flavors, initial reaction intermediates in model systems of glucose–glutathione with hexanal, (E)-2-heptenal, or (E,E)-2,4-decadienal were identified by HPLC–MS and by NMR. Besides Amadori compounds, hemiacetals and thiazolidines via addition of sulfhydryl to carbonyl or to the conjugated olefinic bond were found. Concentrations of all intermediates increased with reaction time while degradation of the intermediates with a glutathione moiety helped formation of thiazolidines with cysteinylglycine. The unsaturated aldehydes (E)-2-heptenal and (E,E)-2,4-decadienal exhibited high reactivity against glucose for glutathione, yielding higher levels of intermediate compounds than from glucose. Heating prepared intermediates reversibly released the original aldehydes, which caused various compounds formed by retro-aldol, oxidation, etc. to react with H2S and NH3. Among them, formation pathways including 3-nonen-2-one, 2-hexanoylfuran, and six dialkylthiophenes (e.g., 2-ethyl-5-(1-methylbutyl)thiophene) were proposed for the first time.
- Wang, Tianze,Zhen, Dawei,Tan, Jia,Xie, Jianchun,Cheng, Jie,Zhao, Jian
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- 1,1-vinyl substituted nonlinear optical materials
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Nonlinear optical compounds having structures with delocalized resonance configurations corresponding to: STR1 wherein A1 and A2 are independently selected from electron withdrawing moieties; R1 and R2 are independently selected from aromatic rings, heteroaromatic rings and fused ring systems consisting of two or three aromatic or heteroaromatic rings; n and m are integers from one to five, and D1 and D2 are independently selected from hydrogen, electron donating groups and polymer attachment groups, with the proviso that at least one of D1 and D2 is an electron donating group. Polymers blended with, cured with, or having pendant side chains of the disclosed nonlinear optical materials and exhibiting second order nonlinear optical properties are also disclosed.
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