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11.
The electrochemical copolymerization of furan and thiophene was performed at a constant electrode potential in a binary solvent system consisting of boron trifluoride/ethyl ether and an additional amount of ethyl ether (molar ratio = 1 : 2). The obtained homopolymers and copolymers were characterized with cyclic voltammetry and infrared spectroscopy. The influence of the applied electropolymerization potential and the monomer feed ratio of furan and thiophene on the copolymers was investigated. The furan–thiophene copolymers showed good stability of the redox activity in an acetonitrile‐based electrolyte solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
12.
Rudolf Felix 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(2):129-135
Real world applications of a decision model of relationships between goals based on fuzzy relations are presented. In contrast
to other approaches the relationships between decision goals or criteria for each decision situation are represented and calculated
explicitly. The application fields are decision making for financial services and optimization of production sequences in
car manufacturing. 相似文献
13.
Rudolf E. Schmitt Johann Haas und Renato Amadò 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1988,187(2):121-124
Zusammenfassung Zur Bestimmung biogener Amine aus Schlachtgeflügel wird ein einfach durchzuführendes Analysenverfahren beschrieben. Die Amine wurden mit 0,6m-Perchlorsäure extrahiert, nach Dansylierung auf einer RP-18 Säule aufgetrennt und bei 254 nm detektiert. Innerhalb von 7 min konnte eine gute Auftrennung von 8 Aminen erreicht werden. Zur quantitativen Erfassung von Spermin und Spermidin mußte der Extrakt zusätzlich über Amberlite CG 50 gereinigt werden. Die Wiederfindungsraten betrugen 82% bis 96%, die Nachweisgrenzen 0,2 bis 0,5 g pro g Hühnerhaut. Bei Schlachtgeflügel eignen sich Putrescin und Cadaverin gut als Leitsubstanzen für den einsetzenden Verderb, da sie bereits ab Gesamtkoloniezahlen von etwa 105 pro cm2 nachweisbar sind, und ihre Konzentration mit zunehmendem Verderb rasch ansteigen.
Determination of biogenic amines by RP-HPLC for monitoring microbial spoilage of poultry
Summary A simple high-performance liquid chromatographic (HPLC) analysis is described for the determination of biogenic amines in broiler carcasses. The clean-up procedure consists of an extraction with 0.6M-perchloric acid, formation of dansyl derivatives, separation by a RP-18 column and UV detection at 254 nm. Within 7 min eight amines could be separated. The quantitative determination of spermidine and spermine requires an additional ion-exchange clean-up with Amberlite CG 50 after the extraction. This procedure gives recoveries of 82%–96% with detection limits of 0.2–0.5 g/g of broiler skin. Putrescine and cadaverine are good indicators for the onset of spoilage of poultry carcasses, since both amines could be detected at total colony counts of 105 cfu/cm2 and their concentration increases rapidly with advancing decomposition.相似文献
14.
Smokers Richard Gense Raymond Rijkeboer Rudolf Dijkhuizen Arjan 《Topics in Catalysis》2004,30(1-4):439-443
Topics in Catalysis - This paper presents the results of a quantitatively substantiated “expert judgement” concerning the potential for further reduction of the exhaust emissions of... 相似文献
15.
In Winkel (2001) a generalization of Bernstein polynomials and Bézier curves based on umbral calculus has been introduced. In the present paper we describe new geometric and algorithmic properties of this generalization including: (1) families of polynomials introduced by Stancu (1968) and Goldman (1985), i.e., families that include both Bernstein and Lagrange polynomial, are generalized in a new way, (2) a generalized de Casteljau algorithm is discussed, (3) an efficient evaluation of generalized Bézier curves through a linear transformation of the control polygon is described, (4) a simple criterion for endpoint tangentiality is established. 相似文献
16.
Rudolf H. Scheffrahn Ruei-Ching Hsu Nan-Yao Su Jacob B. Huffman Sharon L. Midland James J. Sims 《Journal of chemical ecology》1988,14(3):765-776
The heartwood of bald cypress,Taxodium distichum (L.) Rich., resisted feeding attack by the Formosan subterranean termite,Coptotermes formosanus Shiraki. Hexane-extracted heartwood, however, was consumed at > 12 times the amount of sound heartwood eaten. A bioassay usingT. distichum sapwood as a feeding substrate was employed to assess the antitermitic activity of successive hexane, acetone, and methanol extracts of heartwood shavings and isolates derived from the active hexane extract. Two fractions, eluted from the crude hexane extract by liquid chromatography, significantly reduced termite feeding compared to the parent extract, while a third fraction was less active than the original hexane extract. Each fraction contained one major component. All three components were structurally related diterpenes. The two most active heartwood constituents were identified by GC-MS and NMR as ferruginol and manool, while the third and least active, but most prevalent, compound in heartwood was identified as nezukol. Results of bioassays suggest that these allelochemicals act principally as feeding deterrents with accompanying termite mortality due to starvation. 相似文献
17.
18.
Miodrag Čolić Sergej Tomić Rebeka Rudolf Evgenija Marković Ivana Šćepan 《Journal of materials science. Materials in medicine》2016,27(8):128
Superelastic (SE) and thermo-activated (TA) nickel–titanium (NiTi) archwires are used in everyday orthodontic practice, based on their acceptable biocompatibility and well-defined shape memory properties. However, the differences in their surface microstructure and cytotoxicity have not been clearly defined, and the standard cytotoxicity tests are too robust to detect small differences in the cytotoxicity of these alloys, all of which can lead to unexpected adverse reactions in some patients. Therefore, we tested the hypothesis that the differences in manufacture and microstructure of commercially available SE and TA archwires may influence their biocompatibility. The archwires were studied as-received and after conditioning for 24 h or 35 days in a cell culture medium under static conditions. All of the tested archwires, including their conditioned medium (CM), were non-cytotoxic for L929 cells, but Rematitan SE (both as received and conditioned) induced the apoptosis of rat thymocytes in a direct contact. In contrast, TruFlex SE and Equire TA increased the proliferation of thymocytes. The cytotoxic effect of Rematitan SE correlated with the higher release of Ni ions in CM, higher concentration of surface Ni and an increased oxygen layer thickness after the conditioning. In conclusion, the apoptosis assay on rat thymocytes, in contrast to the less sensitive standard assay on L929 cells, revealed that Rematitan SE was less cytocompatible compared to other archwires and the effect was most probably associated with a higher exposition of the cells to Ni on the surface of the archwire, due to the formation of unstable oxide layer. 相似文献
19.
We propose a user-centric rule filtering method that allows to identify association rules that exhibit a certain user-specified temporal behavior with respect to rule evaluation measures. The method can considerably reduce the number of association rules that have to be assessed manually after a rule induction. This is especially necessary if the rule set contains many rules as it is the case for the task of finding rare patterns inside the data. For the proposed method, we will reuse former work on the visualization of association rules [M. Steinbrecher, R. Kruse, Visualization of possibilistic potentials, in: Foundations of Fuzzy Logic and Soft Computing, in: Lecture Notes in Comput. Sci., vol. 4529, Springer-Verlag, Berlin/Heidelberg, 2007, pp. 295–303] and use an extension of it to motivate and assess the presented filtering technique. We put the focus on rules that are induced from a data set that contains a temporal variable and build our approach on the requirement that temporally ordered sets of association rules are available, i.e., one set for every time frame. To illustrate this, we propose an ad-hoc learning method along the way. The actual rule filtering is accomplished by means of fuzzy concepts. These concepts use linguistic variables to partition rule-related domains of interest, such as the confidence change rate. The original rule sets are then matched against these user concepts and result in only those rules that match the respective concepts to a predefined extent. We provide empirical evidence by applying the proposed methods to hand-crafted as well as real-world data sets and critically discuss the current state and further prospects. 相似文献
20.
Rudolf Treleano Hans-Dieter Belitz Harald Jugel und Herbert Wieser 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1978,167(5):320-323
Zusammenfassung 1-Aminocycloalkan-l-carbonsäuren mit Ringgrößen von 4–11 (ohne 10) wurden synthetisiert und auf ihre Geschmackseigenschaften untersucht. Süßer Geschmack tritt vom 4-Ring bis zum 8-Ring auf, beim 6-Ring ist der Schwellenwert minimal (c
Ssü=1–3 mmol/l). Bitter sind die Verbindungen vom 5-Ring bis zum 9-Ring, das Minimum des Schwellenwertes liegt beim 8-Ring (c
sbi=2–5 mmol/l). Die größeren Ringe sind bis zu Konzentrationen von 20 mmol/l ohne Geschmack. Beim 6-Ring löscht eine 2-Methylgruppe jeden Geschmackseindruck, während die 3- und 4-Methylverbindungen süß und bitter sind. Die 4-Äthylverbindung ist bitter aber nicht süß, die 4-tert.-Butylverbindung ist ohne Geschmack. 1-Aminonorbornan-1-carbonsäure ist süß (c
Ssü 50 mmol/l) und bitter (c
sbi=5–7mmo1/1), wobei der Schwellenwert für bitter fast eine Zehnerpotenz kleiner ist. tert.-Leucin ist ohne Geschmack. Die Ergebnisse werden im Zusammenhang mit früheren Untersuchungen an offenkettigen Aminosäuren diskutiert und in Modelle über sterische Voraussetzungen für Geschmack eingeordnet.
Relationsships between structure and taste in amino acids with cyclic side chains
Summary 1-Aminocycloalkane-1-carboxylic acids with ring sizes of 4–11 (excluding 10) were synthesized and tested for their taste properties. The compounds with 4- to 8-membered rings are sweet, with threshold values going through a minimum for the 6-membered ring (c tsw = l-3 mM/l). The compounds with 5- to 9-membered rings are bitter. Here the threshold value reaches a minimum for the 8-membered ring (c tbi=2–5 mM/l). The larger rings are without taste up to concentrations of 20 mmol/l. With the 6-membered ring a 2-methyl group abolishes any taste impression, whereas the 3- and 4-methyl compounds are sweet and bitter. The 4-ethyl compound is bitter but not sweet, the 4-tert.-butyl compound has no taste. 1-Aminonorbornane-l-carboxylic acid is sweet (c tsw 50mM/l) and bitter (c tbi= 5–7 mM/l), withc tbi being significantly smaller thanc tsw. tert-Leucine is without taste. The results are discussed in relation to previous investigations into steric prerequisites for taste in the amino acid series.相似文献