Search results for "pero"

Involvement of Peroxynitrite on the Early Loss of P450 in Short-Term Hepatocyte Cultures

2001

The biological chemistry of nitric oxide (NO) in the oxygenated cellular environment is extremely complex. It involves the direct interaction of NO with specific biomolecules and the so-called indirect effects, due to secondary more potent oxidant species derived from NO which are also able to react with DNA, lipids, thiols and transition metals (Wink et al. 1996; Nathan, 1992). In addition to its regulatory role as a signalling molecule (Nathan, 1992; Moncada and Palmer, 1991) it has become evident that NO (or NO-derived species) is a critical factor involved in various toxicological mechanisms (Wink et al. 1996; Wang et al. 1998; Estevez et al. 1999; Wink et al. 1999). Some controversy ex…

Der nachweis der primärreaktion bei der autoxydation des tetralins

1964

Die Autoxydation des Tetralins wurde bei kleinen Umsatzen durch polarographische oder kolorimetrische Bestimmung des Peroxidgehaltes verfolgt und eine Anfangsgeschwindigkeit gefunden, die groser ist, als sie nach dem Peroxidgehalt des Tetralins sein sollte. Diese zusatzliche Reaktionsgeschwindigkeit ist die der Primarreaktion der Autoxydation. Dabei bilden sich aus Tetralin und molekularem Sauerstoff Radikale. Diese Primarreaktion ist nur dann beobachtbar, wenn der Peroxidgehalt des Tetralins etwa 10−5 Mol/l betragt oder kleiner ist. The autoxidation of tetraline was measured to a low degree of conversion by polarographic or colorimetric determination of tetraline hydroperoxide. The extrapo…

Über die photosensibilisierte autoxydation von polyvinylalkohol

1968

Polyvinylalkohol wurde in wasriger Losung bei 30°C unter Belichtung mit einer Quecksilberhochdrucklampe einer mit benzophenn-3.3′-disulfonsaurem Natrium photosensibilisierten Autoxydation unterworfen. Als Reaktionsprodukte wurden Wasserstoffperoxid, Sauren und Kohlendioxid ermittelt. Unter den gewahlten Reaktionsbedingungen werden die Makromolekule statistisch abgebaut. Viskositatsmessungen und analytische Bestimmungen zeigen, das pro Spaltung der polymerkette nur eine Carboxylendgruppe entsteht. Ein Reaktionsmechanismus wird diskutiert. Polyvinylalcohol was oxidized in water solution at 30°C by irradiation with a mercury high pressure lamp and benzophenon-3.3′-disodiumdisulfonate as sensit…

Synthesis of Lead Zirconate Antiferroelectric Thin Films by Sol-Gel Processing

2000

A modified methoxyethanol sol-gel process was used for the production of PbZrO3 thin films. The new route uses lead oxide [PbO] instead of lead acetate [Pb(OAc)2]. Through the use of this method it is possible to prepare single-phase perovskite materials with improved properties. Examples are given for PbZrO3 thin layers deposited by the spin coating process on TiO2/Pt/TiO2/SiO2/Si substrates from various sols where lead acetate or lead oxide are used as the starting lead compound. The preferred orientation and the perovskite phase content of the films were studied using X-ray diffraction analysis (XRD). Scanning electron microscopy (SEM) was used for microstructural characterization of the…

ChemInform Abstract: Baeyer-Villiger Oxidation of Ketones with a Silica-Supported Peracid in Supercritical Carbon Dioxide under Flow Conditions.

2009

[2-Percarboxyethyl]-functionalized silica reacts with ketones in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions to yield the corresponding esters and lactones. The solid reagent can be easily recycled through treatment with 70% hydrogen peroxide in the presence of an acid at 0 °C. This procedure not only simplifies the isolation of the reaction products, but has the advantage of using only water and carbon dioxide as solvents under mild conditions.

Catalytic properties of the trivalent lanthanide oxides in the decomposition of hydrogen peroxide

2017

Przeanalizowano katalityczne właściwości tlenków trójwartościowych lantanowców w reakcji redukcji nadtlenku wodoru do tlenu gazowego i wody. Jest to reakcja modelowa w badaniach aktywności katalitycznej związków stosowanych jako katalizatory elektrody tlenowej, co oznacza, że dobry katalizator reakcji rozkładu nadtlenku wodoru w roztworze będzie również dobrym katalizatorem procesów zachodzących na elektrodzie tlenowej. Na podstawie wolumetrycznych danych określających objętość wydzielonego tlenu w czasie wyznaczono stałe szybkości reakcji katalizowanych wybranymi tlenkami lantanowców dla temp. 298 i 318 K oraz energie aktywacji.

Über die authoxydation ungesättigter verbindungen. VI. Mitt. Die autoxydation des 9,11-octadecadiensäuremethylesters

1956

9,11-Octadecadiensauremethylester reagiert mit molekularem Sauerstoff in 1,2- und 1,4-Stellung unter Bildung von relative niedermolekularen Sauerstoff-Copolymerisation. Diese polymeren Peroxyde sind bei der Authoxydation autokatalytisch wirksam. Sie sind recht bestandig; die buldung von Aldehyden wurde dei der Aufbewahrung nicht beobachtet. Die Reaktion von end- und von kettenstandigen Doppelbindungen, die in Nachbarschaft zu Peroxygruppen stechen, mit Perbenzoesaure wird am Beispiel des Allyl-tert.-Butyl- und des Cyclohexenylmethylperoxyds untersucht. The Me-ester of 9,11-octadecadienoic acid reacts in 1.2 and 1.4-position with moleculare oxygen to give relatively low molecular oxygen-copo…

Catalytic combustion of ethane over high surface area Ln1−xKxMnO3 (Ln = La, Nd) perovskites: The effect of potassium substitution

1997

Publisher Summary As a general trend, the substitution of the rare earth cation by potassium decreased the intrinsic activity, reduced the reaction order in oxygen, and, for the more substituted samples (x>0.10), it increased the selectivity to ethene. Supported platinum or palladium catalysts have so far been used almost exclusively, because of their excellent activity. However, their high price, tendency to be poisoned, and volatility in some applications have estimulated the search for suitable substitutes. LaCoO3, as a potential auto exhaust catalyst, starting a wide interest in the catalytic properties of perovskites. Their specific application as catalysts in flameless combustion has …

Unique Features of the Low Molecular Weight Probe Salicylaldehyde in the Detection of Nanomolar Peroxynitrite Fluxes

2012

The bleaching efficacy of carbamide peroxide gels containing potassium nitrate desensitizer

2020

Background To evaluate the bleaching efficacy of at-home carbamide peroxide (CP) gels in two concentrations, containing or not a desensitizing agent. Material and methods Forty incisors were divided into four groups (n=10), according to gel concentrations (10% or 22%), and presence or not of 3% potassium nitrate in the gel. A thin layer of gel was applied to the buccal surface of each tooth for 2h/day for 4 weeks. Bleaching efficacy was measured using a spectrophotometer, and ∆E*ab, ∆E00 and ∆WID were calculated. Measurements were performed at baseline, 7, 14, 21, 28, and 35 days following the first gel application. Data were analyzed by two-way RM-ANOVA and Tukey's test (α=0.05). Results R…