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폴리에틸렌 테레프탈레이트와 폴리트리메틸렌 테레프탈레이트의 공중합체 합성과 특성 분석(I) - 중합조건의 영향 -
박양호,노석균,김준호 한국섬유공학회 1999 한국섬유공학회지 Vol.36 No.7
Random copolyesters were prepared from poly (ethylene terephtalate) (PET) oligomer and 1,3-propanediol (PG) by polycondensation procedure using varying amounts of PET oligomer and PG. Copolymer compositions have been identified by $^1$H-NMR spectroscopy. The compositions of the copolymers can be conveniently controlled by manipulation of the reaction conditions. Three hour polymerization at 26$0^{\circ}C$ generated the copolymers with the highest intrinsic viscosity. Investigation of the thermal properties of the obtained polymers via DSC showed that the copolyester became completely amorphous when the composition of PG ranged from 30 to 65%. Sequence information of the produced copolyesters were obtained from $^{13}C$-NMR analysis. The ET-TP-ET and TT-TP-TT blocks could be distinguished from the unsymmetrical diester sequence ET-TP-TT. The sequence analysis indicates that all the studied copolymers have randomly distributed sequence structure.
박양호,서범석 한국원예학회 2011 Horticulture, Environment, and Biotechnology Vol.52 No.4
For verification that ascorbic acid can affect on the process of nitrite reduction, reduced form of ascorbic acid (AsA)dissolved in the pH 7.5 buffer solution was added and vacuum-infiltrated into spinach (Spinacia oleracea L.) leaf sections. The endogenous nitrite was reduced in accordance with AsA oxidation by the higher rate with addition of AsA than that without it. In addition, when 15N-labelled nitrite was added to the leaf sections together with AsA, higher 15N contents were found in ammonia and the reduced soluble form of N (ammonia and amino acids) within short periods in the leaf sections treated with AsA than without it. The crude enzymes in the leaf extract from spinach leaves could reduce nitrate to nitrite in the presence of AsA but the rate was less than that in the presence of NADH. Formation of nitric oxide from nitrite by nitrate reductase in leaf extract in the presence of AsA (at pH 7.5) was estimated to be insignificant. Addition of AsA and (Fd) ferredoxin to the leaf extract could reduce nitrite at higher rate than that of NADPH(Nicotinamide Adenine Dinucleotide Phospate)-FNR(Ferredoxin NADP+ Reductase) -Fd system. These results suggest the possible electron donation from AsA to nitrite reduction via Fd in the dark.