A computer-controlled pulse radiolysis system

Patterson, L. K.; Lilie, J.

doi:10.1016/0020-7055(74)90020-5

Cited by 122 publications

(36 citation statements)

References 8 publications

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“…Pulse radiolysis measurements were made with a computerized system similar to that described earlier [8]. Some modifications in data treatment have been made to utilize a Hewlett-Packard 9830A calculator off-line [9].…”

Section: Methodsmentioning

confidence: 99%

Pulse Radiolysis Studies in Model Lipid Systems. The Influence of Aggregation on Kinetic Behavior of OH Induced Radicals in Aqueous Sodium Linoleate

Patterson

Hasegawa

1978

Ber Bunsenges Phys Chem

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The effect of the solvent composition and of micelle-forming surfactants on the electron-transfer rate between phenothiazine and iron(III), according to the reaction asp + Fe(lI1) e &n + Fe(ll)Solvent composition affects the specific rate constant k l in the order: methanol/water > ethanol/water > n-propanol/water > acetone/water (all 50/50 v.v.).Strong effect is exhibited by micelles in going from a large increase observed for anionic surfactant to a decrease for non-ionic or cationic ones, in respect to the previous cited solvent compositions. The difference in reaction rate observed between an anionic surfactant and a cationic one is about lo4 -10'. The effect of acidity, ionic strength and temperature has been also investigated. E 4097 H H has been investigated by means of the stopped-flow technique.The kinetic and spectral behavior of radicals formed by hydroxyl radical attack on linoleate anions has been studied by pulse radiolysis. Reactivity of .OH toward this surfactant is an order of magnitude greater in monomeric form [k,OH+linolca,c = 8.0. lo9 M -' sec-I] than in micellar form [k.OH+lin(mico,lc) = 1.0' lo9 M-' sec-'1. Abstraction of a hydrogen atom from the doubly allylic position gives rise to an intense absorption in the UV region (Amax = 282-286nm, E -3 . lo4 M-' cm-' ) which may be used as a probe of radical activity at that site. This abstraction may occur, to a small extent, directly via .OH attack. However, greater than 90% of initial attack occurs at other sites. Subsequent secondary abstraction of doubly allylic H atoms appears to occur predominantly by: (1) intramolecular processes in monomers, (2) intermolecular processes in micelles. Disappearance of radicals by secondary processes is slower in the micellar pseudo phase than in monomeric solution.Die kinetischen und spektralen Eigenschaften von Radikalen, die durch die Reaktion von OH-Radikalen mit Linoleat-Anionen entstehen, wurden mit der Pulsradiolyse untersucht. Die Reaktivitat von OH ist gegeniiber dem monomeren Linoleat-Anion etwa eine GroDenordnung groBer (koH+Linolsa, = 8,O' lo9 M -' s -I als gegeniiber der mizellaren Form (koH+Lin(M,rellc) = 1.0. lo9 M -' S -' ). Abspaltung eines Wasserstoffatoms von der zweifachen Allylposition fuhrt zu einer intensiven Absorption im UV-Bereich (Amax = 282-286 nm, E -lo4 M-'), die als Sonde fur die Radikalaktivitat an dieser Stelle dienen kann. Mehr als 90% der OH-Radikale greifen jedoch an anderen Stellen des Molekiils an. Die darauf folgende sekundare Abspaltung von H-Atomen in der zweifachen Allylposition scheint hauptsiichlich durch 1) intramolekulare Prozesse in Monomeren und 2. intermolekulare Prozesse in Mizellen zu erfolgen. Das Verschwinden von Radikalen durch Sekundirprozesse geschieht in der mizellaren Pseudophase langsamer als in der monomeren Losung.cis double-bond moieties incorporated into their mid-zone. Such moieties may consist of one double bondas in the case of oleic acidor multiple non-conjugated bonds as in the cases of linoleic and linolenic acids. *) The research described...

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Section: Methodsmentioning

confidence: 99%

Pulse Radiolysis Studies in Model Lipid Systems. The Influence of Aggregation on Kinetic Behavior of OH Induced Radicals in Aqueous Sodium Linoleate

Patterson

Hasegawa

1978

Ber Bunsenges Phys Chem

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“…The relative absorbance, A , is defined by A = N X log 10 (IJI) (1) In this equation I 0 is the incident intensity £(X) = number of X radicals formed for 100 eV of the radiation absorbed by the system (4) and additional information on special purifications and other precautions.…”

Section: Explanation Of Display and Definition Of Symbols And Unitsmentioning

confidence: 99%

Optical spectra of nonmetallic inorganic transient species in aqueous solution

Hug¹

1981

143

141

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“…The doses used here were approximately 20 Gy. The principles of the detection system have been previously described (15). A Corning O-51 optical filter, removing all wavelengths shorter than 350 nm, was placed in the analyzing light beam to avoid direct flumequine photochemistry.…”

Section: Methodsmentioning

confidence: 99%

A Laser Flash Photolysis and Pulse Radiolysis Study of Primary Photochemical Processes of Flumequine¶

Bazin¹,

Bosca²,

Marin³

et al. 2007

Photochemistry and Photobiology

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The 355 nm laser flash photolysis of argon‐saturated pH 8 phosphate buffer solutions of the fluoroquinolone antibiotic flumequine produces a transient triplet state with a maximum absorbance at 575 nm where the molar absorptivity is 14 000 M−1 cm−1. The quantum yield of triplet formation is 0.9. The transient triplet state is quenched by various Type‐1 photodynamic substrates such as tryptophan (TrpH), tyrosine, N‐acetylcysteine and 2‐deoxyguanosine leading to the formation of the semireduced flumequine species. This semireduced form has been readily identified by pulse radiolysis of argon‐saturated pH 8 buffered aqueous solutions by reaction of the hydrated electrons and the CO2·− radicals with flumequine. The absorption maximum of the transient semireduced species is found at 570 nm with a molar absorptivity of 2500 M−1 cm−1. In argon‐saturated buffered solutions, the semireduced flumequine species formed by the reaction of the flumequine triplet with TrpH stoichiometrically reduces ferricytochrome C (Cyt Fe3+) under steady state irradiation with ultraviolet‐A light. In the presence of oxygen, O2·− is formed but the photoreduction of Cyt Fe3+ by O2·− competes with an oxidizing pathway which involves photo‐oxidation products of TrpH.

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A computer-controlled pulse radiolysis system

Cited by 122 publications

References 8 publications

Pulse Radiolysis Studies in Model Lipid Systems. The Influence of Aggregation on Kinetic Behavior of OH Induced Radicals in Aqueous Sodium Linoleate

Pulse Radiolysis Studies in Model Lipid Systems. The Influence of Aggregation on Kinetic Behavior of OH Induced Radicals in Aqueous Sodium Linoleate

Optical spectra of nonmetallic inorganic transient species in aqueous solution

A Laser Flash Photolysis and Pulse Radiolysis Study of Primary Photochemical Processes of Flumequine¶

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