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21.
Theodor Severin und Karl-Heinz Bräutigam 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1970,144(5):321-323
Zusammenfassung Erhitzt man Phenylalanin, N-Acetylphenyläthylamin oder N-Glycyl-phenylalanin alleine oder mit Triglyzeriden in Gegenwart von Luft auf Temperaturen um 190–200° C, so wird Benzaldehyd gebildet.
Formation of benzaldehyde from phenylalanine and phenylethylamine by heating under air blast
Summary Benzaldehyde is formed when phenylalanine, n-acetyl-phenylethylamine or n-glycyl-phenylalanine alone or with triglycerides in presence of air are heated to a temperature of nearly 190–200° C.相似文献
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Interaction was studied between pyruvate dehydrogenase (EC 1.2.4.1) and C-4'-substituted analogs of thiaminpyrophosphate, 4'-N (CH3)-TPP, 4'-N(CH3)2-TPP and OH-TPP. None of these analogs was found to replace TPP during the reduction of NAD and 2.6-dichlorophenol-indophenol as well as pyruvate decarboxylation. The decarboxylase activity of the pyruvate dehydrogenase component isolated from the pyruvate dehydrogenase complex was determined according to the 14CO2 yield and production of 2-C-oxoethyl-TPP using 1-14C-pyruvate and 2-14C-pyruvate, as substrates, respectively. All the analogs were found to competitively inhibit pyruvate dehydrogenase, Ki values for 4'-N(CH3)-TPP, 4'-N(CH3)2-TPP and 4'-OH-TPP being 4.1 X 10(-5) M, 8.5 X 10(-5) M and 2.9 X 10(-6) M, respectively; Km values for TPP was equal to 1-2 X 10(-7) M. It is assumed that the analogs of the holoenzymic complex formed by the pyruvate dehydrogenase component of the pyruvate dehydrogenase complex with mono-, dimethyl-TPP and oxo-TPP do not bind the substrate. 相似文献
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Gebhard Manninger und Theodor Severin 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1976,161(1):45-51
Zusammenfassung Dihydroxyaceton reagiert mit Methylammoniumacetat in wäßriger Lösung beim Erhitzen rasch unter Bräunung. Von den mit Methylenchlorid extrahierbaren Produkten konnten die heterocyclischen Verbindungen 1 bis 30 isoliert und größtenteils identifiziert werden.
Reaction of dihydroxyacetone with methylammoniumacetate studies on the Maillard-Reaction, X
Summary By heating dihydroxyacetone and methylammoniumacetate in aqueous solution, a deeply brown coloured reaction mixture is obtained. The products extractable with methylenechlorid were separated. Several heterocyclic compounds (1–30) could be identified.相似文献
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Advanced Maillard reaction in proteins leads to formation of covalently cross-linked aggregates the chemical nature of which is largely unknown. From model reactions of methylglyoxal and butylamine with creatine or alpha-N-acetyl-L-arginine, one main product each was isolated. These two compounds were identified, on the basis of unequivocal spectroscopic evidence, as 2-[(5-butylimino-4-methyl-4,5-dihydro-1H-2-imidazolyl)(methyl)amin o]acetic acid and 2-acetylamino-5-[(5-butylimino-4-methyl-4,5-dihydro-1H-2-imidazoly l)amino]pentanoic acid, respectively. Using D-glucose instead of methylglyoxal, two main products each were obtained from reaction with the respective guanidine derivative. The spectroscopic data definitively establish the formation of the diastereoisomeric 2-[(4-butyl-6,7-dihydroxy-4,5,6,7,8,8a-hexahydroimidazo[4,5-b]a zepin-2-yl)(methyl)amino]acetic acid from the reaction with creatine, and of the diastereoisomeric 2-acetylamino-5-[(4-butyl-6,7-dihydroxy-4,5,6,7,8,8a-hexahydroimidazo [4,5-b]azepin-2-yl)amino]pentanoic acid from the reaction with alpha-N-acetyl-L-arginine. All products were isolated in fairly good yield and represent 1:1:1 adducts of the respective reaction partners. Formation of these compounds thus constitutes an efficient reaction pathway for linking primary amines to guanidine derivatives. It seems justified, therefore, to expect cross-linking of proteins by action of reducing carbohydrates to proceed analogously. 相似文献
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Linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) differ significantly in their branching types and branching distributions. For a comprehensive analysis, preparative temperature rising elution fractionation and/or preparative molar mass fractionation are used to fractionate typical LLDPE and LDPE bulk resins into narrowly distributed fractions. The chain structures of the bulk resins and their fractions are further analysed using SEC, crystallization analysis fractionation, DSC and high‐temperature HPLC to provide detailed information on short chain branching in LLDPE and long chain branching in LDPE. For LDPE it is shown that the multiple fractionation approach is a powerful source of sample libraries that may have similar molar masses and different branching structures or alternatively similar branching but different molar masses. The analysis of these library samples by thermal analysis provides a much deeper insight into the molecular heterogeneity of the samples compared to bulk sample analysis. © 2018 Society of Chemical Industry 相似文献
29.
Trutz Theuer Dominik Schäfer Lucy Dittrich Markus Nohl Severin Foit Ludger Blum Rüdiger-A. Eichel L. G. J. de Haart 《化学,工程师,技术》2020,92(1-2):40-44
High-temperature co-electrolysis shows comparable performance to steam electrolysis. Current densities above 1 A cm−2 can be reached between 700 °C and 800 °C. Tailor-made syngas is produced, mainly determined by the reactant ratio. The experimental results are supported by modeling. Durability tests with cathode-supported cells show increased voltage degradation rates during electrolysis compared to fuel cell operation. Nickel depletion is found to be the main cause. 相似文献
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Severin N Groeper S Kniprath R Glowatzki H Koch N Sokolov IM Rabe JP 《Ultramicroscopy》2008,109(1):85-90
We investigated the scattering of current-voltage data obtained with scanning tunneling spectroscopy (STS) at room temperature at a solid-liquid interface on highly oriented pyrolytic graphite (HOPG) and in ultrahigh vacuum on HOPG and Au(111). For both experimental conditions, the data scattering can be described by a lognormal function for a moderate number of subsequent measurements. The lognormal distribution of the current can be explained by a normal distribution of the tip-surface distance. We give a simple empirical rule for STS data sorting. 相似文献