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showing 10 items of 1921 documents
Direct involvement of acid centers of polyaniline in charge transfer on organic acceptor
1996
Abstract Electrochemical behavior of hydroquinone and 4F-hydroquinone has been studied on Pt/polyaniline (PANI) electrodes in 1 M H 2 SO 4 solution. Redox transformation of quinone/hydroquinone systems takes place on PANI practically without overpotential and, probably, the two-electron charge transfer processes are realized in such systems. Reaction currents depend on PANI quantities deposited on the Pt electrode and the molecular complex is formed. There exists a great electronic exchange between acid centers of PANI and quinone/hydroquinone molecules, resulting in electronic conjugation of this surface state (adsorbed molecule) with the polymer. Existence of such complexes was confirmed …
Molecular orbital study of conformational isomers and rotational barriers of methyl substituted hydroquinone cation radicals
1998
Abstract The torsional potential energy curve of the hydroxyl group of hydroquinone and tetramethyl-hydroquinone cation radicals were explored with various ab initio methods. The minimum and the torsional transition state geometries and energies were computed by using high accuracy density functional methods yielding the rotation barrier height and the energy difference between the cis- and trans-isomers. The obtained minimum energy geometry for the hydroquinone cation radical indicates that the CO bond has shortened when compared to the neutral species. We attribute this to the increased double-bond character of this bond. The energy minima were located for methyl-hydroquinone, 2,3-dimeth…
Arylated phenols, aroxyl radicals and aryloxenium ions syntheses and properties
1985
C3-Symmetric Ligands for Catalysis
2008
Protection by beverages, fruits, vegetables, herbs, and flavonoids against genotoxicity of 2-acetylaminofluorene and 2-amino-1-methyl-6-phenylimidazo…
2002
Abstract Chinese hamster lung fibroblasts, genetically engineered for the expression of rat cytochrome P450 dependent monooxygenase 1A2 and rat sulfotransferase 1C1 (V79-rCYP1A2-rSULT1C1 cells), were utilized to check for possible protective effects of beverages of plant origin, fruits, vegetables, and spices against genotoxicity induced by 2-acetylaminofluorene (AAF) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Antigenotoxic activities of juices from spinach and red beets against AAF could be monitored with similar effectivity by the HPRT-mutagenicity test (IC50=0.64%; 2.57%) and alkaline single cell gel electrophoresis (comet assay; IC50=0.12%; 0.89%) which detects DNA stran…
De Kosala a Bollywood: dos mil años contando historias. Un estudio semiótico del ramayana
2008
El Rāmāyaa se originó en el norte de la India entre los siglos IV a.C. y IV d.C. Contiene elementos fantásticos, míticos, legendarios y religiosos. Los jainistas y los budistas escribieron sus propios rāmāyaas para criticar aspectos del brahmanismo y difundir sus doctrinas. La literatura sánscrita se inspiró en la leyenda de Rāma y la historia también se incluyó en los purāas. En el siglo V aparecieron las primeras narrativas visuales, paneles esculpidos en los templos que se leen como secuencias cinematográficas. La devoción y el culto a Rāma se popularizaron con el movimiento devocional (bhakti) y se compusieron rāmāya&#…
Dažu ivabradīna sintēzes stadiju pētījumi
2018
Dažu ivabradīna sintēzes stadiju pētīšana. Lugovskojs R., zinātniskie vadītāji MSc. Reine I. un Dr. chem. doc. Kļimenkovs I. Bakalaura darbs, 36 lappuses, 25 attēli, 3 tabulas, 24 literatūras avoti. Latviešu valodā. Darbā ir pētītas triju svarīgo ivabradīna starpproduktu - 7,8-dimetoksi-1H-benzo[d]azepin-2(3H)-ona, 3-(3-hlorpropil)-7,8-dimetoksi-1H-dihidro-2H-3-benzo[d]azepin-2(3H)-ona un dehidroivabradīna iegūšanas metodes ar mērķi atrast optimālus reakcijas apstākļus, kas piemēroti sintēzes veikšanai rūpnieciskā mērogā. Darbā ir apkopota pieejamā literatūra par ivabradīna un tā svarīgāko starpproduktu iegūšanas metodēm. Īpaši ir pētīta 7,8-dimetoksi-1H-benzo[d]azepin-2(3H)-ona alkilēšana,…
Inhibition of imidazolidinone intermediate formation in the aldol reactions catalyzed by zinc–prolinamide complexes
2011
Abstract The use of zinc salts as cocatalysts in aldol condensations catalyzed by single prolinamide (and in the extension by other more complex prolinamides) can prevent the formation of the parasitic intermediate imidazolidinone, with faster and also more stereoselective reactions than those catalyzed by the free amine. This new finding, together with this ion’s already known properties, make zinc salts highly suitable additives for aldol reactions catalyzed for prolinamide derivatives.
In silico methods for metabolomic and toxicity prediction of zearalenone, α-zearalenone and β-zearalenone.
2020
Zearalenone (ZEA), α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL) (ZEA's metabolites) are co/present in cereals, fruits or their products. All three with other compounds, constitute a cocktail-mixture that consumers (and also animals) are exposed and never entirely evaluated, nor in vitro nor in vivo. Effect of ZEA has been correlated to endocrine disruptor alterations as well as its metabolites (α-ZEL and β-ZEL); however, toxic effects associated to metabolites generated once ingested are unknown and difficult to study. The present study defines the metabolomics profile of all three mycotoxins (ZEA, α-ZEL and β-ZEL) and explores the prediction of their toxic effects proposing an in silico w…
NQS-Doped PDMS Solid Sensor: From Water Matrix to Urine Enzymatic Application
2021
The development of in situ analytical devices has gained outstanding scientific interest. A solid sensing membrane composed of 1,2-naphthoquinone-4-sulfonate (NQS) derivatizing reagent embedded into a polymeric polydimethylsiloxane (PDMS) composite was proposed for in situ ammonium (NH4+) and urea (NH2CONH2) analysis in water and urine samples, respectively. Satisfactory strategies were also applied for urease-catalyzed hydrolysis of urea, either in solution or glass-supported urease immobilization. Using diffuse reflectance measurements combined with digital image processing of color intensity (RGB coordinates), qualitative and quantitative analyte detection was assessed after the colorime…