Mechanisms of one-electron capture by slow He2+, C4+ and O6+ ions in collisions with CH4

Translational energy spectroscopy (TES) has been used to study one-electron capture by He2+, C4+, and O6+ ions in collisions with CH4 within the range 200 - 2000 eV amu—1. In each case the main collisions mechanisms and product channels have been identified. The measurements reveal significant differences in the way the dissociative and non-dissociative mechanisms contribute to electron capture. However, in all cases, the highly selective nature of the charge transfer process is confirmed in spite of the wide range of energy defects associated with possible product channels.

Energy analysis of hyperthermal hydrogen atoms generated through surface neutralisation of ions

Hydrogen ions (H+, H-2(+) and H-3(+)) are produced in a magnetically confined inductively coupled radio frequency plasma. Ions are accelerated in the plasma boundary sheath potential, of several hundred volts, in front of a biased metal electrode immersed in the plasma. Backscattered hyperthermal hydrogen atoms are investigated by optical emission spectroscopy and an energy-resolved mass spectrometer. Ionisation of fast neutrals through electron stripping of atoms in the plasma allows energy analysis of the resulting ions. Thereby, the energy distribution function of the hyperthermal atoms can be deduced. The energy spectra can be explained as a superposition of individual spectra of the various ion species. The measured spectra also shows contributions of negative ions created at the electrode surface. In addition to experimental measurements, simulations of the neutral flux of backscattered atoms are carried out.

Evidence for Strong Breit Interaction in Dielectronic Recombination of Highly Charged Heavy Ions

Resonant strengths have been measured for dielectronic recombination of Li-like iodine, holmium, and bismuth using an electron beam ion trap. By observing the atomic number dependence of the state-resolved resonant strength, clear experimental evidence has been obtained that the importance of the generalized Breit interaction (GBI) effect on dielectronic recombination increases as the atomic number increases. In particular, it has been shown that the GBI effect is exceptionally strong for the recombination through the resonant state [1s2s(2)2p(1/2)](1).

Two-electron QED contributions to the ground-state binding energy in He-like Kr34+ ions

The two-electron QED contributions to the ground-state binding energy of Kr34+ ions have been determined in two independent experiments performed with electron beam ion traps (EBIT) in Heidelberg (HD) and Tokyo (BT, Belfast-Tokyo collaboration). X rays arising from radiative recombination (RR) of free electrons to the ground state of initially bare Kr36+ and hydrogenlike Kr35+ ions were observed as a function of the interacting electron energy. The K edge absorption by thin Eu and W foils provided fixed photon energy references used to measure the difference in binding energy Delta E-2e between the H- and He-like Kr ions (Kr35+ and Kr34+, respectively). The two values agree well, yielding a final result of Delta E-2e=641.8 +/- 1.7 eV, confirming recent results of rigorous QED calculations. This accuracy is just of the order required to access screened radiative QED contributions.

Effects of low energy carbon ions on plasmid DNA

The damage induced in supercoiled plasmid DNA molecules by low energy (< 1 keV u-1) singly and doubly charged carbon ions has been investigated as a function of ion exposure. The production of short linear fragments through multiple double strand breakage is indicated and exponential exposure responses for each of the topoisomers are presented. The damage produced by C2+ is apparent at much lower ion exposures that with C+.

Positive dilations of piecewise monotonic Markov maps

We provide an explicit formula which gives natural extensions of piecewise monotonic Markov maps defined on an interval of the real line. These maps are exact endomorphisms and define chaotic discrete dynamical systems.

Energy levels and radiative rates for transitions in B-like to F-like Kr ions (Kr XXXII-XXVIII)

Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Kr ions, Kr XXXIII-XXVIII. For the calculations, the fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 125, 236, 272, 226, and 113 levels of Kr XXXII, Kr XXXI, Kr XXX, Kr XXIX, and Kr XXVIII, respectively, belonging to the n

Increased anti-tumour efficacy of doxorubicin when combined with sulindac in a xenograft model of an MRP-1-positive human lung cancer

Background: A number of cellular proteins, including P-glycoprotein (P-gp) and Multiple drug Resistance Protein (MRP-1), act as drug efflux pumps and are important in the resistance of many cancers to chemotherapy. We previously reported that a small number of NSAIDs could inhibit the activity of MRP-1. Materials and Methods: We chose sulindac as a candidate agent for further investigation as it has the most favourable efficacy and toxicity profile of the agents available for a potential specific MRP-1 inhibitor. NCI H460 cells expressed MRP-1 protein (by Western blot) and also the toxicity, of doxorubicin (a substrate of MRP-1) could be potentiated in this line using non-toxic concentrations of the MRP-1 substrate/inhibitor sulindac. These cells were implanted in nude mice and the animals divided into various groups which were administered doxorubicin and/or sulindac. Results: Sulindac was shown to significantly potentiate the tumour growth inhibitor activity of doxorubicin in this MRP-1-overexpressing human tumour xenograft model. Conclusion: Sulindac may be clinically useful as an inhibitor of the MRP-1 cancer resistance mechanism.