Search results for "cyclic"
showing 10 items of 2439 documents
Wechselwirkungen zwischen Acetylsalicylsäure und Lysin in Lösung
1985
Der pH-abhangige Einflus von Lysin auf die Hydrolyse von Acetylsalicylsaure zu Salicylsaure und auf die Bildung von Lysinderivaten der Acetylsalicylsaure wurde durch HPLC-Untersuchungen geklart. Die Bildung von e-N-Acetyl-lysin, α-N-Acetyl-lysin und wenig Diacetyl-lysin erfolgt rasch bei pH-Werten der Losung von 6 und hoher, sehr langsam jedoch bei dem fur gebrauchliche Injektionslosungen eingestellten pH-Wert 5. Das Auftreten des postulierten Salicyloyllysins in Acetylsalicylsaure-Lysin-Losungen wurde durch Vergleich mit der unabhangig synthetisierten Verbindung ausgeschlossen. Interactions of Acetylsalicyclic Acid and Lysine in Solution The influence of lysine on the hydrolysis, and on th…
Die Herstellung einer molekulareinheitlichen Tetramethacrylsäure mittels verschiedener Matrizen. VI. Mitt. Modelle für Matrizenreaktionen
1968
Es wurde aus einer phenolischen Zweikernverbindung eine cyclische Verbindung IV hergestellt, die bei der alkalischen Hydrolyse eine molekulareinheitliche Tetramethacrylsaure (VII) und die phenolische Ausgangsverbindung gab. Die Synthese der gleichen Saure (VII) gelang auch mit strukturell verschiedenen Zweikernverbindungen, wenn nur bei den verwendeten Matrizen der innermolekulare Abstand der beiden phenolischen Hydroxylgruppen fur die Reaktion gunstig war. Alkaline hydrolysis of a cyclic compound (IV) which was prepared out of a dinuclear phenolic compound gave a molecularly homogeneous tetra-methacrylic acid (VII) and the original phenolic compound. The synthesis of the same acid could al…
Modelling electrocatalysis of hydroquinone oxidation by nicotinamide adenine dinucleaotide coenzyme encapsulated within SBA-15 and MCM-41 mesoporous …
2006
The electrochemical response of NADH associated to two mesoporous aluminosilicates, MCM-41 and SBA-15, is described upon attachment of such materials into polymer-film electrodes. The studied materials display a significant electrocatalytic activity towards the oxidation of 1,4-dihydrobenzoquinone, H2Q. Two models for describing the electrocatalytic process, based on the general theory of mediated electrocatalysis and the Lovric and Scholz formulation of the voltammetry of microparticles are discussed. Voltammetric and chronoamperometric data indicate that the electrocatalytic process involves the formation of a surface-confined NADH–H2Q adduct in the case of SBA-15, while a surface reactio…
Electrochemistry of hydrotalcite-supported bis(2-mercapto-2,2-diphenyl-ethanoate) dioxomolybdate complexes.
1998
The redox properties of the hydrotalcite-intercalated bis(2-mercapto-2,2-diphenyl-ethanoate) dioxomolybdate(VI) complex are investigated by cyclic voltammetry by using modified carbon paste electrodes and clay-modified electrodes. The electrochemical data provide evidence that boundary-associated species involving the VI, V and IV oxidation states of molybdenum are responsible for the electroactivity.
Selective Synthesis of New Fluorinated Alicyclic β-Amino Ester Stereoisomers (Eur. J. Org. Chem. 26/2011)
2011
The cover picture shows a waterfall located in the Eastern Carpathians in Transylvania, near Bicaz Canyon. Although fluorinated organic compounds are nonexistent in nature, an increasing number of drugs (25 %) on the market contain at least one fluorine atom. Cyclic fluorinated β-amino acid derivatives have been synthesized by selective hydroxylation and hydroxy?fluorine exchange. Details are discussed in the article by F. Fulop et al. on p. 4993 ff.
A Selective Synthesis of Fluorinated Cispentacin Derivatives
2014
A facile selective method has been developed for the synthesis of new fluorine-containing cispentacin stereoisomers. Mono- and difluorinated cispentacin derivatives were synthetized from a bicyclic β-lactam in five or six steps involving a regio- and stereoselective hydroxylation through iodooxazoline formation, followed by deoxygenation by fluorination. Starting from an enantiomerically pure bicyclic β-lactam obtained by enzymatic resolution of the racemic compound, an enantiodivergent procedure allowed the preparation of both dextro- and levorotatory difluorinated cispentacins.
Non-equivalent hyperbolic knots
2002
We construct, for each integer n 3, pairs of non-equivalent hyperbolic knots with the same 2fold and n-fold cyclic branched covers. We also discuss necessary conditions for such pairs of knots to exist. 2001 Elsevier Science B.V. All rights reserved. MSC: primary 57M25; secondary 57M12, 57M50
Misdiagnosis and pitfalls in Panayiotopoulos syndrome
2019
Abstract Panayiotopoulos syndrome (PS) is a frequent (6% among children of 1–15 years) and benign epileptic syndrome, characterized by predominantly autonomic symptoms (emesis, pallor, flushing, cyanosis, mydriasis/miosis, cardiorespiratory and thermoregulatory alterations, incontinence of urine and/or feces, hypersalivation, and modifications of intestinal motility) associated with simple motor focal seizures, which can be followed by secondary generalization. Panayiotopoulos syndrome can be extremely insidious, because it can mimic several condition, such as gastroenteritis, gastroesophageal reflux disease, encephalitis, syncope, migraine, sleep disorders, or even metabolic diseases. This…
Differential disease resistance response in the barley necrotic mutant nec1
2010
Abstract Background Although ion fluxes are considered to be an integral part of signal transduction during responses to pathogens, only a few ion channels are known to participate in the plant response to infection. CNGC4 is a disease resistance-related cyclic nucleotide-gated ion channel. Arabidopsis thaliana CNGC4 mutants hlm1 and dnd2 display an impaired hypersensitive response (HR), retarded growth, a constitutively active salicylic acid (SA)-mediated pathogenesis-related response and elevated resistance against bacterial pathogens. Barley CNGC4 shares 67% aa identity with AtCNGC4. The barley mutant nec1 comprising of a frame-shift mutation of CNGC4 displays a necrotic phenotype and co…
The Cyclicality of Bank Credit Losses and Capital Ratios under Expected Loss Model
2023
We model the evolution of stylised bank loan portfolios to assess the impact of IFRS 9 and US GAAP expected loss model (ECL) on the cyclicality of loan loss provisions (LLPs), realised losses and capital ratios of banks, relative to the incurred loss model of IAS 39. We focus on the interaction between the changes in LLPs charges (the flow channel) and stocks (the stock channel) under ECL. Our results show that, when GDP growth doesn’t demonstrate high volatility, ECL model smooths the impact of credit losses on profits and capital resources, reducing the pro-cyclicality of capital and leverage ratios, especially under US GAAP. However, when GDP growth is highly volatile, the large differen…