Neue Modifizierung der Methode der Injektionsenthalpimetrie.

Ohne Zusammenfassung     

Neue Modifizierung der Methode der Injektionsenthalpimetrie.

Ohne Zusammenfassung     

Thermal stability, antioxidant activity, and photo-oxidation of natural polyphenols

The thermal stability (60°C, 80°C, 100°C), antioxidant activity, and ultraviolet C light (UV-C) stability of standard polyphenols solutions (catechin, gallic acid, and vanillic acid) and of vegetal extracts from spruce bark and grape seeds were investigated. Exposure of the standard solutions and vegetal extracts to high temperatures revealed that phenolic compounds were also relatively stable (degradations ranged from 15 % to 30 % after 4 h of exposure). The highest antioxidant activity was obtained for ascorbic acid and gallic acid followed by catechin and caffeic acid and the grape seeds. The results show that, after 3 h of UV-C exposure, approximately 40 % of vanillic acid, 50 % of gallic acid, and 83 % of catechin were removed. Similar degradation rates were observed for vegetal extracts, with the exception of the degradation of catechin (40 %) from grape seeds. In addition, the photo-oxidation of polyphenols in the presence of food constituents such as citric acid, ascorbic acid, sodium chloride, and sodium nitrate was assessed.     

‘Statistical methods for automatic crack detection based on vibrothermography sequence‐of‐images data’ by M. Li,S. D. Holland and W. Q. Meeker: Discussion 1

In the following notes I comment the paper of Liitet al., mainly from the point of view of its original contribution to the methods of analysis of special image data. In particular, I concentrate on several questions connected with the proposed procedure and its results. Copyright © 2010 John Wiley & Sons, Ltd.     

Die isosterische Adsorptionswärme an heterogenen Oberflächen

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Die isosterische Adsorptionsw?rme an heterogenen Oberfl?chen

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Novel Potentiometric Sensor for Determination of Cysteine Based on Substituted Poly(diphenylporphyrins and Metalloporphyrins

This paper describes the application of an electropolymerized film of poly(bis(2-aminophenyl)-2,8,12,18-tetraethyl-3,7,13, 17-tetramethylporphyrin) and its metalloderivative for determination of amino acids. A remarkable selectivity for cysteine (log K _{Cys/Amino acids} ^pot = 10^–2–10^–3) has been found. The potentiometric response to sulfur-containing amino acids is discussed and compared with selectivity data for PVC-membranes based on metallotetraphenylporphyrins.     

A graphical characterization of the largest chain graphs

The paper presents a graphical characterization of the largest chain graphs which serve as unique representatives of classes of Markov equivalent chain graphs. The characterization is a basis for an algorithm constructing, for a given chain graph, the largest chain graph equivalent to it. The algorithm was used to generate a catalog of the largest chain graphs with at most five vertices. Every item of the catalog contains the largest chain graph of a class of Markov equivalent chain graphs and an economical record of the induced independency model.     

Monomer and polymer quinoxaline derivatives for cationic recognition

Monomeric and polymeric 5-nitroquinoxaline derivatives disubstituted in the 2 and 3 positions with 2-pyrrolyl (A), 2-furyl (B) and 2-thienyl (C) groups were prepared and characterized. The substituted 5-nitroquinoxalines were used as active components in poly(vinyl chloride)-membrane and electropolymerized electrodes that were then tested as possible sensors for various cationic species. In contrast to the difurylnitroquinoxaline-based systems, the monomeric and polymeric dipyrrolyl- and dithienylquinoxaline electrodes displayed a good selectivity for Ag(+) ions, providing a near-Nernstian response in the 10(-5) to 10(-2) mol L(-1) concentration range. The similar potentiometric behavior displayed by the monomeric and polymeric forms of systems A and C supports the contention that the main binding modes displayed by the monomeric forms are retained in the corresponding polymeric structures.