Properties Of Free Radicals Research Articles

Магнитные свойства свободных радикалов

Магнитные свойства свободных радикалов

A topological method for determining the external symmetry number of molecules

Abstract A method for determining the external symmetry number of molecules and free radicals is described. The method of calculation is based on a topological approach, mainly by means of a factorized representation of molecules and free radicals. The input of formulae into the computer is achieved by a linear notation. The corresponding program is a part of a more important software dealing with the computation of thermochemical properties of molecules and free radicals in the gas phase.

Magnetic properties of free radicals

Magnetic properties of free radicals

Магнитные свойства радикалов

Магнитные свойства радикалов

A comparison of the free radical properties of several anthracycline anti-tumour drugs and some of their analogues.

NADPH consumption and esr spectroscopy have been used to study the rate of formation and signal intensity of free radicals produced by various anthracycline anti-tumour drugs in rat liver microsomal extract. The drugs investigated were Adriamycin, 4'Deoxyadriamycin, Daunorubicin, 4 Demethoxydaunorubicin and Carminomycin. Pulse radiolysis was also used to determine the case of reduction of each of the analogues to its semiquinone radical and some kinetic properties of the radicals produced. It is believed that the occurrence of reactions other than dismutation could be responsible for the shortened lifetimes of the semiquinone radicals observed in biological systems.

Free radical properties of native and solubilized eu-and pheo-melanins

Free radical properties of native and solubilized eu-and pheo-melanins

Comparison of dna scission and cytotoxicity produced by adriamycin and 5-iminodaunorubicin in human colon carcinoma cells

The quinone-modified anthracycline, 5-iminodaunorubicin, which does not spontaneously generate free radicals, was compared to Adriamycin on the basis of DNA-protein crosslink-associated single-strand breakage, cell lethality, and the pharmacokinetics of drug uptake and efflux in human colon carcinoma cells in culture. At equivalent cytocidal concentrations, 5-iminodaunorubicin produced more single-strand breakage of DNA than Adriamycin after a 2-hr treatment interval, but the DNA scission produced by 5-iminodaunorubicin rapidly disappeared after drug removal. The kinetics of DNA breakage correlated with the rapid rates of uptake and efflux of 5-iminodaunorubicin in comparison to Adriamycin. These data emphasize the importance of the cellular pharmacokinetics of anthracyclines in relation to their cytocidal and DNA damaging properties. Moreover, the induction of equivalent single-strand breakage of DNA by similar intracellular concentrations of both drugs suggests that the free radical properties of Adriamycin are not involved in DNA scission.

A theoretical investigation of the properties of free radicals.

Results of Unrestricted Hartree-Fock calculations, at various basis set levels, are used for rationalizing static and dynamic properties of free radicals. A detailed classification of these species, based on their electronic structure and their stabilization energy, is presented. The latter concept is shown to be a good tool for analyzing the self-reactivity of free radicals.

A theoretical investigation of the properties of free radicals

Results of Unrestricted Hartree-Fock calculations, at various basis set levels, are used for rationalizing static and dynamic properties of free radicals. A detailed classification of these species, based on their electronic structure and their stabilization energy, is presented. The latter concept is shown to be a good tool for analyzing the self-reactivity of free radicals.

Chemical and magnetic properties of muonic free radicals in solutions of styrene in benzene

Download options Please wait... Article information DOI https://doi.org/10.1039/F19827802975 Article type Paper Download Citation J. Chem. Soc., Faraday Trans. 1, 1982,78, 2975-2995 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Chemical and magnetic properties of muonic free radicals in solutions of styrene in benzene S. F. J. Cox, A. Hill and R. de Renzi, J. Chem. Soc., Faraday Trans. 1, 1982, 78, 2975 DOI: 10.1039/F19827802975 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Stephen F. J. Cox Alyson Hill Roberto de Renzi

Redox properties of free radicals

This article will concentrate on reactions with organic compounds which involve an electron transfer, i.e.., redox reactions.

Properties of Free Radicals in Protein and Amino Acid Pyrolysates

ABSTRACTThe ESR intensities (g=2.0042 ∼ 2.0053) of free radicals in L‐lysine and casein pyrolysates increased with increase of the heating time. In L‐lysine pyrolysate (200°C, 20 min), the fraction insoluble in organic solvents and water accounted for 48.1% of the ESR intensity of the whole pyrolysate; the component responsible appeared to be a product of condensation polymerization, but the elemental analysis data indicated a smaller value for nitrogen than that expected for polylysine. The pyrolysis of casein brought about denatured products insoluble in water. The free radicals formed were stable for a week in distilled water and were unaffected by digestion with pepsin or pancreatin (37°C for 3 hr).

Laser Spectroscopy of Negative Ion Beams

The availability of intense tunable and fixed frequency lasers has made it possible to investigate photon-ion interactions in crossed beam experiments. The short wavelength limitations of current lasers result in the greatest variety of applications having been made to studies of photon interactions with negative ions. Two major experimental approaches have been developed: fixed frequency laser negative ion photoelectron spectroscopy and tunable laser photode-tachment/photodissociation spectroscopy. The former approach is best suited for determination of electron affinities and structural properties of ions and free radicals, while the latter method provides highly accurate electron affinities and dynamical information on electron-molecule interactions. It is also possible to determine the internal energy content of negative ions. The experimental techniques and their limitations will be discussed in the form of several case studies: OH , C2 and the transition metals. Finally an attempt will be made to ascertain promising avenues for new investigations in this field.

Book reviews

Abstract Pioneers of Science. By Robert L. Weber. (Institute of Physics, 1980.) [Pp. xviii + 272.] £9.95. The Excitation and Propagation of Elastic Waves. By J. A. Hudson. (Cambridge University Press, 1980.) [Pp. viii + 226.] Scope: Treatise; Survey. Level: Specialist/postgraduate. Non-linear Oscillations. By A. H. Nayfeth and D. J. Mook. (John Wiley, 1979.) [Pp. xiv + 704.] £21.35. Scope: Survey. Level: Postgraduate/research. Advances in X-ray Analysis, Volume 23. Edited by J. R. Rhodes and others. (Plenum Press, 1980.) [Pp. xii + 390.] $45.00. Defects and Diffusion in Solids: an Introduction. By S. Mrowéc. (Elsevier/Polish Scientific Publishers, 1980.) [Pp. 466.] $83.00, Dfl. 170.00. Fundamentals of Crystal Growth. By F. Rosenberger. (Springer-Verlag, 1979.) [Pp. x +530.] DM79; $43.50. Secondary Ion Mass Spectrometry—SIMS II. Edited by A. Benninghoven and others. (Springer-Verlag, 1979.) [Pp. 298.] $34.30. The Papers of Joseph Henry, Volume 3. The Princeton Years 1836 and 1837. Edited by Nathan Reingold. (Smithsonian Institution Press, Washington, 1979.) Phonon Scattering in Condensed Matter. Edited by H. J. Maris. (Plenum Press, 1980.) [Pp. xix + 481.] $52.50. Scope: State-of-the-art review. Level: Postgraduate research. Atomic Masses and Fundamental Constants. Edited by J. A. Nolen Jr. and W. Benenson. (Plenum Press, 1980.) [Pp. xiii + 572.] $59.50. The Strangest Star. By John Gribbin. (The Athlone Press, 1980.) [Pp. 183.] £6.95. Scope: General astrophysics and some geophysics. Level: Non-specialist. Microcircuit Engineering. By H. Ahmed and W. C. Nixon. (Cambridge University Press, 1980.) [Pp. x + 585.] £20.00. Scope: Conference report. Level: For specialists. The Rare Earths in Modern Science and Technology. Volume 2. Edited by G. J. McCarthy, J. J. Rhyne and H. B. Silber. (Plenum Press, 1980.) [Pp. xxiii + 647.] $59.50. Scope: Specialist. Level: Advanced. Current Topics in Materials Science, Volume 3. Edited by E. Kaldis. (North-Holland, 1979.) [Pp. 688.] Dfl.230. Scope: Recent developments. Level. Postgraduate, specialist. Physics of Semiconductor Devices. By G. H. B. Thompson. (John Wiley, 1980.) [Pp. xxv + 549.] B2.75. Vibrational Spectroscopy of Molecular Liquids and Solids. Edited by S. Bratos and R. M. Pick. (Plenum Press, 1980.) [Pp. ix+464.] $49.50. Scope: Highly specialized theoretical treatment of topics in the title. Level: Advanced research. The Physics of Nuclear Reactions. By W. M. Gibson. Second edition. (Pergamon Press, 1980.) [Pp. vii+338.] $15.00. Scope: Low energy reactions including reactors and thermonuclear processes. Level: Undergraduate. Is the End in Sight for Theoretical Physics? An Inaugural Lecture. By Stephen Hawking. (Cambridge University Press, 1980.) [Pp. 26.] £1.25. From Atoms to Quarks. By J. S. Trefil. (Athlone Press, 1980.) [Pp. xi+225.] £7.50. Phonon Dispersion Relations in Insulators. By H. Bilz and W. Kress. (Springer-Verlag, 1979.) [Pp. vii + 241.] DM 84; $46.20. ISBN 3 540 09377–0. European Journal of Physics. Edited by G. W. Series. A Journal of the European Physical Society, published quarterly by the Institute of Physics. Volume 1, No. 1, August 1980. Energy and Environmental Balance. By EARL FINBAR MURPHY. (Pergamon Press, 1980.) [Pp. vii+280.] $2500. Marine Sources of Energy. By JACQUES CONSTANS. (Pergamon Press, 1980.) [Pp. xxv +168.] $1500. Landolt-B$oUrnstein. Numerical Data and Functional Relationships in Science and Technology. Group II. Volume 9: Magnetic Properties of Free Radicals, Part d2. Organic Cation Radicals and Polyradicals. By R. A. Forrester, K. Ishizu, G. Kothe and S. F. Nelson. (Springer-Verlag, 1980.) [Pp. xii + 369.] DM 470, $277.30. Physics Unified. By Harold Aspden. (Sabberton Publications, 1980.) [Pp. xiv + 206.] £3.00 paperback. Hands-on Applied Physics. By A. McAlexander. (Addison-Wesley, 1979.) [Pp.ix + 398.] £11.40. Scope: Classbook. Level: Elementary. Physics in Perspective. By E. Hecht. (Addison Wesley, 1980.) [Pp. xi + 532.] £11.65.

Free radicals in coals and coal conversion. 2. Effect of liquefaction processing conditions on the formation and quenching of coal free radicals

Free radicals are generally accepted as playing an important role in the liquefaction of coal. In a continuing series of studies, we are attempting to determine the relation between the nature and properties of free radicals and process variables such as residence time in a reactor, heating rates to achieve highest temperature and the role of various solvents and gases in stabilizing free radicals in lower-molecular-weight moieties. The free radical concentration after thermal treatments correlates well with the propensity of a given solvent to donate its hydrogen.

NADPH-dependent melanin pigment formation from 5-hydroxyindolealkylamines by hepatic and cerebral microsomes

Incubation of 5-hydroxytryptophan, 5-hydroxytryptamine, 5-hydroxytryptophol and 5-hydroxyindoleacetic acid with rat liver or brain microsomes in the presence of an NADPH-generating system and molecular oxygen caused the formation of microsomal protein-bound melanin-like pigment. The free radical property of this pigment was proved by electron spin resonance spectroscopy. The formation of the pigment was inhibited by superoxide dismutase which indicates the participation of superoxide anion radical in this type of melanogenesis.

Application of Electron Beam Pulse Radiolysis to Chemical Research

The application of the electron pulse technique to chemical systems has been responsible for a substantial advance in the study of chemical processes. This has been achieved by opening up certain fields e.g. reactions and properties of electrons ions and free radicals which could not develop using classical methods. The power and versatility of the method is well demonstrated by the fact that activity in its application is still increasing and new areas in which it can be applied are continually being introduced.

Development and current problems in radiation chemistry

Radiation chemistry has developed mainly as a branch of chemical kinetics. Many reactions are known today in a detailed manner and powerful electronic methods for the investigation of short lived intermediates such as pulse radiolysis and in situ electron spin resonance absorption have been developed. These methods are today applied to other fields of physical chemistry. The following applications will be mentioned: properties of free radicals, investigation of complex redox reactions in homogeneous solution, reactions in micellar systems, electron pool reactions in aqueous solution, radiation driven phosphorylation, and excess electrons in dielectric liquids.

Interrelationship of spectral and photochemical properties of stable free radicals and biradicals

Interrelationship of spectral and photochemical properties of stable free radicals and biradicals

Properties of small-ring free radicals. 2. Thermal decomposition of alicyclic percarboxylates

Properties of small-ring free radicals. 2. Thermal decomposition of alicyclic percarboxylates