Low-Energy Positronium Scattering from O2

The total cross-section of positronium scattering from molecular oxygen has been measured in the velocity range 0.27 − 1.50 a.u. (energy range 2 − 61 eV) and found to be close to the corresponding equivelocity electron cross-section above 0.87 a.u. (20 eV), as previously found by Brawley et al. Science 330 789 (2010). However, below this value the cross-section for positronium is observed to exceed that for electrons by up to a factor of 4 at the lowest energy. Measurements are compared to the predictions of low-energy resonant peaks in the elastic scattering cross-section calculated within a free-electron-gas model refined by applying corrections to the correlation energy for the interaction between Ps and the electron gas. Additionally, cross-sections for O− 2 formation and positronium break-up have been calculated using a classical trajectory Monte Carlo approach. Comparisons are made with earlier calculations and discussed in terms of both experimental and theoretical uncertainties

Electron capture from H

The dynamics of the electron capture by He+ ions from H2 molecule has been investigated in the four-body first Born approximation. Cross sections differential in the scattering angle of the projectile ion have been calculated for various molecular orientations. The calculations account for the interference effects due to the coherent scattering of the particles from the two atomic centers. Total cross sections (integrated over the projectile’s scattering angle and averaged over all the molecular orientations) have also been calculated by a three-body version of the classical trajectory Monte Carlo (CTMC) method based on use of a two-center molecular potential, as well as in a semi-classical quasi-molecular model. The obtained total cross sections are compared with the available experimental data and other theoretical calculations. For impact energies above 40 keV a reasonable agreement has been found between the present theoretical results and the experiment

Characterization of new, efficient Mycobacterium tuberculosis topoisomerase-I inhibitors and their interaction with human ABC multidrug transporters

Drug resistant tuberculosis (TB) is a major worldwide health problem. In addition to the bacterial mechanisms, human drug transporters limiting the cellular accumulation and the pharmacological disposition of drugs also influence the efficacy of treatment. Mycobacterium tuberculosis topoisomerase-I (MtTopo-I) is a promising target for antimicrobial treatment. In our previous work we have identified several hit compounds targeting the MtTopo-I by in silico docking. Here we expand the scope of the compounds around three scaffolds associated with potent MtTopo-I inhibition. In addition to measuring the effect of newly generated compounds on MtTopo-I activity, we characterized the compounds' antimicrobial activity, toxicity in human cells, and interactions with human multidrug transporters. Some of the newly developed MtTopo-I inhibitors have strong antimicrobial activity and do not harm mammalian cells. Moreover, our studies revealed significant human ABC drug transporter interactions for several MtTopo-I compounds that may modify their ADME-Tox parameters and cellular effects. Promising new drug candidates may be selected based on these studies for further anti-TB drug development