67 research outputs found
Quasiparticle contribution to heat carriers relaxation time in DyBaCuO from heat diffusivity measurements
It is shown that the controversy on phonons or electrons being the most
influenced heat carriers below the critical temperature of high-T
superconductors can be resolved. Electrical and thermal properties of the same
DyBaCuO monodomain have been measured for two highly different
oxygenation levels. While the oxygenated sample DyBaCuO has very
good superconducting properties ( K), the DyBaCuO
sample exhibits an insulator behavior. A careful comparison between
measurements of the {\bf thermal diffusivity} of both samples allows us to
extract the electronic contribution. This contribution to the relaxation time
of heat carriers is shown to be large below and more sensitive to the
superconducting state than the phonon contribution.Comment: 13 pages, 6 figure
The T7-Related Pseudomonas putida Phage Ï•15 Displays Virion-Associated Biofilm Degradation Properties
Formation of a protected biofilm environment is recognized as one of the major causes of the increasing antibiotic resistance development and emphasizes the need to develop alternative antibacterial strategies, like phage therapy. This study investigates the in vitro degradation of single-species Pseudomonas putida biofilms, PpG1 and RD5PR2, by the novel phage ϕ15, a ‘T7-like virus’ with a virion-associated exopolysaccharide (EPS) depolymerase. Phage ϕ15 forms plaques surrounded by growing opaque halo zones, indicative for EPS degradation, on seven out of 53 P. putida strains. The absence of haloes on infection resistant strains suggests that the EPS probably act as a primary bacterial receptor for phage infection. Independent of bacterial strain or biofilm age, a time and dose dependent response of ϕ15-mediated biofilm degradation was observed with generally a maximum biofilm degradation 8 h after addition of the higher phage doses (104 and 106 pfu) and resistance development after 24 h. Biofilm age, an in vivo very variable parameter, reduced markedly phage-mediated degradation of PpG1 biofilms, while degradation of RD5PR2 biofilms and ϕ15 amplification were unaffected. Killing of the planktonic culture occurred in parallel with but was always more pronounced than biofilm degradation, accentuating the need for evaluating phages for therapeutic purposes in biofilm conditions. EPS degrading activity of recombinantly expressed viral tail spike was confirmed by capsule staining. These data suggests that the addition of high initial titers of specifically selected phages with a proper EPS depolymerase are crucial criteria in the development of phage therapy
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