A Sting in the Tail of Electron Tracks

Abstract

mantle (8). The water decreases the melting temperature, resulting in partial melting. Some high-pressure partitioning experiments suggest that, when partial melting occurs in subducted crustal materials, hollandite can preferentially incorporate several incompatible elements (K, Pb, Sr, light rare earth elements, and so forth) but is not likely to be a host for uranium and heavy rare earth elements, relative to the coexisting melt (9). Therefore, the stability of hollandite will strongly influence trace element geochemistry of magmas produced in the deep mantle as well as alkali transport processes in the transition zone and the lower mantle.Detailed studies of shocked meteorites may provide further evidence for dense minerals stable in the deep mantle. Other alkali-host minerals such as calcium ferrite-type NaA1Si04 and a related structural phase (1, 10) may be found in shocked meteorites. Together with comprehensive experimental studies on the melting relations and trace element partitioning between the alkali-host minerals, silicate melt, and fluid at the pressuretemperature conditions of the transition zone and the lower mantle, they will shed light on the behavior of alkali elements in the deep mantle and on crust formation processes. A Sting in the Tail ofing counterparts of ' OH (principally the hydrated electron, e,;;) are relatively ineffective, especially at inducmg DNA strand breaks.

Absolute cross sections for elastic electron scattering from methylformamide

“…It has been shown that secondary low-energy electrons can cause significant, energy-dependent single-and double-strand breaks in DNA [5,6]. Since the major part of the energy deposited by ionizing radiation in condensed matter is channeled into the production of abundant low-energy secondary electrons, spectroscopic data and absolute cross-section values for electron impact on biomacromolecules (DNA, proteins) and its constituents are needed in order to improve our understanding of the chain * vraz@ipb.ac.rs of reactions leading to radiation damage.…”

Non-adiabatic interactions in charge transfer collisions

“…In particular, we are interested in collisions between ions and biomolecules, in relation to the action of ionizing radiation on the biological medium [7,20]. Different processes may be induced in such reactions, including: excitation and ionization of the target, fragmentation of the ionized biomolecule, and electron exchange from the incident ion toward the biomolecular system [21].…”

“…Recently, such reactions have also been extensively investigated in relation to lesions induced by irradiation of the biological medium. It has been shown effectively that significant damage to biological tissues may arise due to secondary particles, such as low-energy electrons, radicals or ions, generated on the track after the ionizing radiation has interacted with the biological environment [7]. An investigation at the molecular level of the elementary mechanisms involved is therefore important for understanding more complex biological reactions.…”

Absolute cross sections for electron scattering from furan

“…6,[14][15][16][17][18][19][20] However, it must be taken into account that, contrary to THF, the furan molecule is not saturated and an existence of π orbitals makes it chemically distinct from THF. For example, the process of dissociative electron attachment, which is considered to be particularly important in radiation damage research since it could lead to DNA strand breaks, 1,2 is very different for these. 21 On the other hand, although being chemically very different, furan and THF have a similar structure with the difference being in only four H atoms, so they should also have similar cross sections for elastic electron scattering in the energy range of interest in the present work (above 50 eV), where the independent atom model (a molecular cross section is approximated by a sum over atomic cross sections) starts to be operative.…”

“…Electron interactions with small biomolecules analogue to building blocks of large biological macromolecules (DNA, proteins) have been the subject of considerable interest, since it was discovered that low-energy electrons can cause significant DNA damage. 1,2 The primary, high-energy particle produces a large number of secondary low-energy electrons on its track in the biological medium; therefore, those electrons may play an important role in macroscopic radiation damage of living cells and tissues. Although it is usually considered that the dominant part of the secondary electrons are formed with rather low energies (below about 30 eV), the tail of their distributions can have a significant fraction of electrons with energies of the order of 10 2 eV.…”