Full-wave finite space model of open-ended coaxial line for dielectric spectroscopy of liquids.

The physical equipment was built according to the mathematical model and tested. The performance of equipment is demonstrated measuring two known liquids, methanol and isopropanol, up to 40 GHz. The accuracy and sensitivity, and the versatility and ease of manufacturing of the measurement cell are discussed.

Effective inactivation of food pathogens Listeria monocytogenes and Salmonella enterica by combined treatment of hypericin-based photosensitization and high power pulsed light.

AIMS: The aim of this study was to evaluate the inactivation efficiency of Listeria monocytogenes ATC(L3) C 7644 and Salmonella enterica serovar Typhimurium strain DS88 by combined treatment of hypericin (Hyp)-based photosensitization and high power pulsed light (HPPL). METHODS AND RESULTS: Cells were incubated with Hyp (1 × 10(-5) or 1 × 10(-7) mol l(-1)) in PBS and illuminated with a light λ = 585 nm. For the combined treatment, bacteria were, after photosensitization, exposed to 350 pulses of HPPL (UV light dose = 0·023 J cm(-2)). Fluorescence measurements were performed to evaluate optimal time for cell-Hyp interaction. Results indicate that Hyp tends to bind both Listeria and Salmonella. After photosensitization treatment, Listeria population was reduced 7 log, whereas Salmonella was inactivated just 1 log. Electron photomicrograps of Salmonella and Listeria confirmed that photosensitization induced total collapse of the Listeria cell wall, but not that of Salmonella. After combined photosensitization-HPPL treatment, the population of Listeria was diminished by 7 log and Salmonella by 6·7 log. CONCLUSIONS: Listeria can be effectively inactivated by Hyp-based photosensitization (7 log), whereas Salmonella is more resistant to photosensitization and can be inactivated just by 1 log in vitro. Combined treatment of photosensitization and pulsed light inactivates effectively (6·7-7 log) both the Gram-positive and the more resistant to photosensitization Gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: A new approach to combat Gram-positive and Gram-negative bacteria is proposed, combining photosensitization with high power pulsed light.

Phase diagram of subphtalocyanine ordering on Ag(111).

A model of subphtalocyanine molecules ordering on Ag(111) is proposed. We have demonstrated that the driving force of the ordering into honeycomb and hexagonal close packed patterns is a balance of intermolecular and subphtalocyanine-Ag interactions which can be generally expressed by a potential with infinite exclusion in a sufficiently large number of nearest coordination spheres of Ag(111) lattice and oscillatingly decaying behavior outside the sphere of exclusion. To cope with computational problems due to large size of the molecules compared to the substrate lattice period, we introduce the rescaling of Ag(111) lattice, and took into account an infinite exclusion of first, second, and third neighbors, attraction-of fourth and fifth, and repulsion-of sixth and seventh. The phase diagram is obtained by the lattice gas model using Monte Carlo simulations. Very strong first order phase transitions, causing the two-phase coexistence, were found between disordered and honeycomb as well as between disordered and hexagonal closed packed phases.