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  • Effective cross sections for production of single-strand breaks in plasmid DNA by 0.1 to 4.7 eV electrons.

Effective cross sections for production of single-strand breaks in plasmid DNA by 0.1 to 4.7 eV electrons.

Radiation research (2006-04-04)
Radmila Panajotovic, Frédéric Martin, Pierre Cloutier, Darel Hunting, Léon Sanche
ABSTRACT

We determined effective cross sections for production of single-strand breaks (SSBs) in plasmid DNA [pGEM 3Zf(-)] by electrons of 10 eV and energies between 0.1 and 4.7 eV. After purification and lyophilization on a chemically clean tantalum foil, dry plasmid DNA samples were transferred into a high-vacuum chamber and bombarded by a monoenergetic electron beam. The amount of the circular relaxed DNA in the samples was separated from undamaged molecules and quantified using agarose gel electrophoresis. The effective cross sections were derived from the slope of the yield as a function of exposure and had values in the range of 10(-15)- 10(-14) cm2, giving an effective cross section of the order of 10(-18) cm2 per nucleotide. Their strong variation with incident electron energy and the resonant enhancement at 1 eV suggest that considerable damage is inflicted by very low-energy electrons to DNA, and it indicates the important role of pi* shape resonances in the bond-breaking process. Furthermore, the fact that the energy threshold for SSB production is practically zero implies that the sensitivity of DNA to electron impact is universal and is not limited to any particular energy range.

MATERIALS
Product Number
Brand
Product Description

Tantalum, foil, light tested, 150x150mm, thickness 0.075mm, annealed, 99.9%
Tantalum, foil, light tested, 150x150mm, thickness 0.03mm, as rolled, 99.9%
Tantalum, foil, light tested, 100x100mm, thickness 0.034mm, as rolled, 99.9%
Tantalum, foil, not light tested, 100x100mm, thickness 0.009mm, 99.9%
Tantalum, foil, not light tested, 25x25mm, thickness 0.0005mm, 99.9%
Tantalum, foil, light tested, 100x100mm, thickness 0.03mm, as rolled, 99.9%
Tantalum, foil, not light tested, 25x25mm, thickness 0.0015mm, 99.9%
Tantalum, foil, light tested, 50x50mm, thickness 0.075mm, annealed, 99.9%
Tantalum, foil, light tested, 25x25mm, thickness 0.02mm, 99.9%
Tantalum, foil, light tested, 100x100mm, thickness 0.05mm, annealed, 99.9%
Tantalum, foil, not light tested, 50x50mm, thickness 0.01mm, 99.9%
Tantalum, foil, not light tested, 50x50mm, thickness 0.0015mm, 99.9%
Tantalum, foil, not light tested, 82x100mm, thickness 0.006mm, 99.9%
Tantalum, foil, not light tested, 25x25mm, thickness 0.01mm, 99.9%
Tantalum, foil, not light tested, 25x25mm, thickness 0.001mm, 99.9%
Tantalum, foil, light tested, 25x25mm, thickness 0.006mm, 99.9%
Tantalum, foil, 6mm disks, thickness 0.009mm, 99.9%
Tantalum, foil, 25mm disks, thickness 0.15mm, annealed, 99.9%
Tantalum, foil, 4mm disks, thickness 0.75mm, annealed, 99.9%
Tantalum, foil, 8mm disks, thickness 0.025mm, as rolled, 99.9%
Tantalum, foil, 6mm disks, thickness 0.100mm, annealed, 99.9%
Tantalum, foil, 4mm disks, thickness 0.009mm, 99.9%
Tantalum, foil, 10mm disks, thickness 0.75mm, annealed, 99.9%
Tantalum, foil, 6mm disks, thickness 0.0125mm, 99.9%
Tantalum, foil, 2m coil, thickness 0.025mm, coil width 0.75mm, annealed, 99.9%
Tantalum, foil, 1m coil, thickness 0.03mm, coil width 1.2mm, annealed, 99.9%
Tantalum, foil, 15mm disks, thickness 0.03mm, as rolled, 99.9%
Tantalum, foil, 50mm disks, thickness 0.075mm, annealed, 99.9%
Tantalum, foil, 4mm disks, thickness 0.5mm, annealed, 99.9%
Tantalum, foil, 50mm disks, thickness 0.03mm, as rolled, 99.9%