Temat: radical ions - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Ionic processes in irradiated solid polymers
Autorzy:: Szadkowska-Nicze, M.
Powiązania:: https://bibliotekanauki.pl/articles/147854.pdf
Data publikacji:: 2005
Wydawca:: Instytut Chemii i Techniki Jądrowej
Tematy:: irradiated polymers
radical ions
ion recombination
radiothermoluminescence
relaxation in polymers
Opis:: The reactions of ionic species generated in irradiated polymers (polyethylene, poly(dimethylsiloxane), poly(methyl methacrylate), and poly(ethylene terephthalate)) doped with pyrene, Py, were observed by radiothermoluminescence and complementary absorption spectroscopic measurements. The charge stabilization in polymers and charge transfer to the solute depend on the chemical structure of polymer chains and physical state of the polymer matrix. The recombination of ionic species is stimulated by relaxation processes of polymers. Total neutralization of charges in irradiated polymers occurs at the glass transition temperature of polymers. Mutual recombination of Py radical ions generates singlet excited states of the solute followed by Py monomer and excimer (depending on the solute concentration) fluorescence. Recombination of Py radical cations and negative species from the polymer matrix leads to the formation of Py triplet excited states followed by Py phosphorescence.
Źródło:: Nukleonika; 2005, 50,suppl.2; 45-49
0029-5922
1508-5791
Pojawia się w:: Nukleonika
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Intermediates derived from p-terphenyl in the methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide ionic liquid saturated with carbon dioxide : pulse radiolysis study
Autorzy:: Kocia, Rafał
Powiązania:: https://bibliotekanauki.pl/articles/2173388.pdf
Data publikacji:: 2022
Wydawca:: Instytut Chemii i Techniki Jądrowej
Tematy:: carbon dioxide
ionic liquid
methyltributylammonium bis[(trifl uoromethyl)sulfonyl]imide
p-Terphenyl
pulse radiolysis
radical ions
Opis:: Radiation-induced processes in ionic liquid (IL) methyltributylammonium bis[(trifl uoromethyl)sulfonyl] imide ([MeBu3N][NTf2]) solutions containing p-terphenyl (TP) and saturated with carbon dioxide (CO2) were studied using nanosecond pulse radiolysis technique with UV-vis detection. The transient absorption spectra generated in these solutions were assigned to TP radical anions (TP•–) and triplet excited states (3TP*). Saturation of [MeBu3N][NTf2] solutions with carbon dioxide efficiently takes out presolvated electrons (e–presolv) and solvated electrons (e–solv). On the other hand CO2 is not a scavenger of excited states of TP (1TP*, 3TP*), which in the reaction with triethylamine (TEA) leads to the formation of TP•-.
Źródło:: Nukleonika; 2022, 67, 4; 73--80
0029-5922
1508-5791
Pojawia się w:: Nukleonika
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Generation of ·OH initiated by interaction of Fe2+ and Cu+ with dioxygen; comparison with the Fenton chemistry.
Autorzy:: Urbański, Norbert
Beręsewicz, Andrzej
Powiązania:: https://bibliotekanauki.pl/articles/1044216.pdf
Data publikacji:: 2000
Wydawca:: Polskie Towarzystwo Biochemiczne
Tematy:: superoxide dismutase
autoxidation
catalase
free radical
Fenton reaction
hydroxyl radical
iron ions
copper ions
desferrioxamine
Opis:: Iron and copper toxicity has been presumed to involve the formation of hydroxyl radical (·OH) from H2O2 in the Fenton reaction. The aim of this study was to verify that Fe2+-O2 and Cu+-O2 chemistry is capable of generating ·OH in the quasi physiological environment of Krebs-Henseleit buffer (KH), and to compare the ability of the Fe2+-O2 system and of the Fenton system (Fe2+ + H2O2) to produce ·OH. The addition of Fe2+ and Cu+ (0-20 μM) to KH resulted in a concentration-dependent increase in ·OH formation, as measured by the salicylate method. While Fe3+ and Cu2+ (0-20 μM) did not result in ·OH formation, these ions mediated significant ·OH production in the presence of a number of reducing agents. The ·OH yield from the reaction mediated by Fe2+ was increased by exogenous Fe3+ and Cu2+ and was prevented by the deoxygenation of the buffer and reduced by superoxide dismutase, catalase, and desferrioxamine. Addition of 1 μM, 5 μM or 10 μM Fe2+ to a range of H2O2 concentrations (the Fenton system) resulted in a H2O2-concentration-dependent rise in ·OH formation. For each Fe2+ concentration tested, the ·OH yield doubled when the ratio [H2O2]:[Fe2+] was raised from zero to one. In conclusion: (i) Fe2+-O2 and Cu+-O2 chemistry is capable of promoting ·OH generation in the environment of oxygenated KH, in the absence of pre-existing superoxide and/or H2O2, and possibly through a mechanism initiated by the metal autoxidation; (ii) The process is enhanced by contaminating Fe3+ and Cu2+; (iii) In the presence of reducing agents also Fe3+ and Cu2+ promote the ·OH formation; (iv) Depending on the actual [H2O2]:[Fe2+] ratio, the efficiency of the Fe2+-O2 chemistry to generate ·OH is greater than or, at best, equal to that of the Fe2+-driven Fenton reaction.
Źródło:: Acta Biochimica Polonica; 2000, 47, 4; 951-962
0001-527X
Pojawia się w:: Acta Biochimica Polonica
Dostawca treści:: Biblioteka Nauki

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